In order to enable the shape of the surface of a tire including the shoulder sections thereof to be detected, a tire shape testing device comprises: a first linear light application means (10) for applying linear light to the tread section (8) of the tire; a second linear light application means (12) for applying linear light to the sidewall sections (7) of the tire; a third linear light application means (13) for applying linear light to the shoulder sections (9) and to regions outside the shoulder sections (9); and image capturing means (16) for capturing the images of the linear light applied by the first linear light application means (10), the second light application means, and the third linear light applications means (13) and reflected by the surface of the tire.