diff --git a/include/raytracing.h b/include/raytracing.h
index ced0c54..bfae1b7 100644
--- a/include/raytracing.h
+++ b/include/raytracing.h
@@ -3,10 +3,10 @@
 /*                                                        :::      ::::::::   */
 /*   raytracing.h                                       :+:      :+:    :+:   */
 /*                                                    +:+ +:+         +:+     */
-/*   By: marimiyahara <marimiyahara@student.42.f    +#+  +:+       +#+        */
+/*   By: nkawaguc <nkawaguc@student.42tokyo.jp>     +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2024/12/13 21:26:05 by marimiyahar       #+#    #+#             */
-/*   Updated: 2024/12/17 01:03:24 by marimiyahar      ###   ########.fr       */
+/*   Updated: 2024/12/20 11:17:07 by nkawaguc         ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
@@ -27,6 +27,9 @@ int		intersect_cylinder(t_vec origin, t_vec direction,
 			t_closest_obj *find_obj);
 int		intersect_plane(t_vec origin, t_vec direction, t_closest_obj *find_obj);
 
+double	intersect_cy_top_base(t_vec direction, t_vec oc, t_object *obj);
+double	intersect_cy_bottom_base(t_vec direction, t_vec oc, t_object *obj);
+
 t_vec	subtract(t_vec v1, t_vec v2);
 t_vec	add(t_vec v1, t_vec v2);
 t_vec	scale(t_vec v, double scalar);
diff --git a/src/raytracing/intersect_cy.c b/src/raytracing/intersect_cy.c
index b425695..219f17c 100644
--- a/src/raytracing/intersect_cy.c
+++ b/src/raytracing/intersect_cy.c
@@ -6,7 +6,7 @@
 /*   By: nkawaguc <nkawaguc@student.42tokyo.jp>     +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2024/12/16 00:20:54 by marimiyahar       #+#    #+#             */
-/*   Updated: 2024/12/18 21:57:13 by nkawaguc         ###   ########.fr       */
+/*   Updated: 2024/12/20 11:17:50 by nkawaguc         ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
@@ -15,7 +15,7 @@
 static int	check_intersect(double *t, t_object *obj, t_vec origin,
 				t_vec direction);
 static int	calc_t(t_vec d_proj, t_vec oc_proj, double *t, t_object *obj);
-static int	calc_t_again(t_vec d_proj, t_vec oc_proj,
+static int	calc_t_again(t_vec direction, t_vec oc,
 				double *t, t_object *obj);
 
 int	intersect_cylinder(t_vec origin, t_vec direction, t_closest_obj *find_obj)
@@ -80,27 +80,20 @@ static int	calc_t(t_vec d_proj, t_vec oc_proj, double *t, t_object *obj)
 	return (1);
 }
 
-static int	calc_t_again(t_vec d_proj, t_vec oc_proj, double *t, t_object *obj)
+static int	calc_t_again(t_vec direction, t_vec oc, double *t, t_object *obj)
 {
-	double	divisor;
-	t_vec	vec_from_center;
+	double	t_top;
+	double	t_bottom;
 
-	divisor = dot_product(d_proj, obj->norm_vector);
-	if (divisor == 0)
+	t_top = intersect_cy_top_base(direction, oc, obj);
+	t_bottom = intersect_cy_bottom_base(direction, oc, obj);
+	if (t_top < 0 && t_bottom < 0)
 		return (0);
-	*t = (-(dot_product(oc_proj, obj->norm_vector) + obj->height / 2)
-			/ dot_product(d_proj, obj->norm_vector));
-	vec_from_center = add(add(oc_proj, scale(d_proj, *t)),
-			scale(obj->norm_vector, obj->height / 2));
-	if (*t > 0 && sqrt(dot_product(vec_from_center, vec_from_center))
-		<= obj->radius + 1e-6)
-		return (1);
-	*t = (-(dot_product(oc_proj, obj->norm_vector) - obj->height / 2)
-			/ dot_product(d_proj, obj->norm_vector));
-	vec_from_center = add(add(oc_proj, scale(d_proj, *t)),
-			scale(obj->norm_vector, -obj->height / 2));
-	if (*t > 0 && sqrt(dot_product(vec_from_center, vec_from_center))
-		<= obj->radius + 1e-6)
-		return (1);
-	return (0);
+	if (t_top < 0)
+		*t = t_bottom;
+	else if (t_bottom < 0)
+		*t = t_top;
+	else
+		*t = fmin(t_top, t_bottom);
+	return (1);
 }
diff --git a/src/raytracing/intersect_cy_two_bases.c b/src/raytracing/intersect_cy_two_bases.c
new file mode 100644
index 0000000..1e703c9
--- /dev/null
+++ b/src/raytracing/intersect_cy_two_bases.c
@@ -0,0 +1,53 @@
+/* ************************************************************************** */
+/*                                                                            */
+/*                                                        :::      ::::::::   */
+/*   intersect_cy_two_bases.c                           :+:      :+:    :+:   */
+/*                                                    +:+ +:+         +:+     */
+/*   By: nkawaguc <nkawaguc@student.42tokyo.jp>     +#+  +:+       +#+        */
+/*                                                +#+#+#+#+#+   +#+           */
+/*   Created: 2024/12/20 11:05:30 by nkawaguc          #+#    #+#             */
+/*   Updated: 2024/12/20 11:18:54 by nkawaguc         ###   ########.fr       */
+/*                                                                            */
+/* ************************************************************************** */
+
+#include "../../include/minirt.h"
+
+double	intersect_cy_top_base(t_vec direction, t_vec oc, t_object *obj)
+{
+	const double	invalid_t = -1;
+	double			t;
+	double			divisor;
+	t_vec			vec_from_center;
+
+	divisor = dot_product(direction, obj->norm_vector);
+	if (divisor == 0)
+		return (invalid_t);
+	t = -(dot_product(oc, obj->norm_vector) + obj->height / 2) / divisor;
+	if (t < 0)
+		return (invalid_t);
+	vec_from_center = add(add(oc, scale(direction, t)),
+			scale(obj->norm_vector, obj->height / 2));
+	if (sqrt(dot_product(vec_from_center, vec_from_center)) > obj->radius)
+		return (invalid_t);
+	return (t);
+}
+
+double	intersect_cy_bottom_base(t_vec direction, t_vec oc, t_object *obj)
+{
+	const double	invalid_t = -1;
+	double			t;
+	double			divisor;
+	t_vec			vec_from_center;
+
+	divisor = dot_product(direction, obj->norm_vector);
+	if (divisor == 0)
+		return (invalid_t);
+	t = -(dot_product(oc, obj->norm_vector) - obj->height / 2) / divisor;
+	if (t < 0)
+		return (invalid_t);
+	vec_from_center = add(add(oc, scale(direction, t)),
+			scale(obj->norm_vector, -obj->height / 2));
+	if (sqrt(dot_product(vec_from_center, vec_from_center)) > obj->radius)
+		return (invalid_t);
+	return (t);
+}