1. An apparatus for inspecting a tire, comprising: a plurality of image shooting means located at positions relatively displaced in the circumferential direction so as to shoot images of the circumferential surface of a tire and set for the respective shooting positions different from each other in the axial direction of the tire; a marker inserting means for entering markers in the images shot by all of the image shooting means at the same time when image shooting is being performed by all of the image shooting means while the tire is rotated circumferentially relative to the plurality of image shooting means; and an image synthesizing means for synthesizing the images shot by all of the image shooting means by shifting the markers in accordance with the relative displacements in the circumferential direction of the respective image shooting means.