To measure the shape of a tire with very high accuracy by reproducing the shape of the tire by means of a tire shape measuring means from the position of each point on a measured lattice plane after calculating the position of each point on the lattice plane by means of a calculating means by inputting the picture of the lattice plane of the tire by means of a picture inputting means while the tire is rotated.

The picture of the lattice plane of a tire T is taken with two cameras 22 and 24 by irradiating the lattice plane with light from a stroboscope device 28 while the tire T is rotated at a prescribed speed. The cameras 22 and 24 send the pictures of the lattice plane 14 to a picture processing section 26. Fach point on the lattice plane 14 is found as the intersection of two straight lines L1 and L2. Only first harmonics are fetched from Fourier-transformed pictures and reversely Fourier-transformed. The phase value at each point is found on the basis of the starting point on the lattice plane 14. The lines L1 and L2 are found from the coordinate values corresponding to a point P in a three-dimensional space from the two pictures and the coordinates of the cameras 22 and 24 in the space and the three-dimensional shape of the tire T is obtained from the lines L1 and L2.