PURPOSE: To measure the thickness and shape of a pipe with one measuring apparatus without cutting off the pipe.

CONSTITUTION: When a turntable 44 is rotated, a supporting means, a reference whisker 38, and a detector 40 are integrally moved after the eccentric motion of a pipe 34. The pipe 34 is rotated in the supporting means concurrently with the movement while the outer periphery and the inner periphery of the pipe 34 are kept in contact with the reference whisker 38 and the whisker of the detector 40 respectively. The outer periphery and the inner periphery of the pipe 34 are moved along the reference whisker 38 and the whisker of the detector 40 respectively. The thickness and shape of the pipe 34 are detected while the outer periphery of the pipe 34 is used as a reference.