A tire inner surface imaging method for imaging a tire inner surface, said tire having a central axis of rotation, the method comprising the steps of: setting a mirror (102, 103, 104, 202, 203, 204, 302, 303, 304) in an imaging position by revolving the mirror (102, 103, 104, 202, 203, 204, 302, 303, 304) around a rotation shaft which is parallel to the central axis of rotation of the tire so that the mirror (102, 103, 104, 202, 203, 204, 302, 303, 304) is inserted into a tire cavity region with a portion of an imaging device inserted into an opening of the tire, the imaging device including a light source, the mirror (102, 103, 104, 202, 203, 204, 302, 303, 304), and a camera (105, 205, 305) and being configured so that the mirror (102, 103, 104, 202, 203, 204, 302, 303, 304) revolves around the rotation shaft while an orientation of a surface of the mirror (102, 103, 104, 202, 203, 204, 302, 303, 304) changes to the imaging position; a rotation amount of the rotation shaft, when the mirror (102, 103, 104, 202, 203, 204, 302, 303, 304) is inserted into the tire cavity region, being determined according to an outer diameter of the tire so that an angle of the tilt of the imaging performed by the camera (105, 205, 305) is within an acceptable range from 25° to 35° with respect to the tire circumferential direction scanning a tread inner surface of the tire with slit light by irradiating the tread inner surface with the slit light; and outputting image data generated by the camera (105, 205, 305) imaging a line irradiation region on the tread inner surface from the direction tilted with respect to the tire circumferential direction via the mirror (102, 103, 104, 202, 203, 204, 302, 303, 304) during the scanning with the slit light, the line irradiation region being formed through the irradiation of the slit light. setting a mirror (102, 103, 104, 202, 203, 204, 302, 303, 304) in an imaging position by revolving the mirror (102, 103, 104, 202, 203, 204, 302, 303, 304) around a rotation shaft which is parallel to the central axis of rotation of the tire so that the mirror (102, 103, 104, 202, 203, 204, 302, 303, 304) is inserted into a tire cavity region with a portion of an imaging device inserted into an opening of the tire, the imaging device including a light source, the mirror (102, 103, 104, 202, 203, 204, 302, 303, 304), and a camera (105, 205, 305) and being configured so that the mirror (102, 103, 104, 202, 203, 204, 302, 303, 304) revolves around the rotation shaft while an orientation of a surface of the mirror (102, 103, 104, 202, 203, 204, 302, 303, 304) changes to the imaging position; a rotation amount of the rotation shaft, when the mirror (102, 103, 104, 202, 203, 204, 302, 303, 304) is inserted into the tire cavity region, being determined according to an outer diameter of the tire so that an angle of the tilt of the imaging performed by the camera (105, 205, 305) is within an acceptable range from 25° to 35° with respect to the tire circumferential direction scanning a tread inner surface of the tire with slit light by irradiating the tread inner surface with the slit light; and outputting image data generated by the camera (105, 205, 305) imaging a line irradiation region on the tread inner surface from the direction tilted with respect to the tire circumferential direction via the mirror (102, 103, 104, 202, 203, 204, 302, 303, 304) during the scanning with the slit light, the line irradiation region being formed through the irradiation of the slit light.