PURPOSE: To make it possible to execute flaw detection in the circumferential and axial directions stably and precisely in regard to ultrasonic flaw detection of a rotating body.

CONSTITUTION: A rotatory support device 11 supporting a test body 10 rotatably, a detecting means 14 which detects directly the rotational position of the test body supported by the rotatory support device 11, a water tank 13 in which a part or the whole of the test body 10 is immersed in a contact medium 12, an ultrasonic probe which is disposed in the contact medium 12 and executes inspection of the inside of the test body 10, and a data storage device 33 which stores ultrasonic flaw detection signal data at each rotational position of the test body according to a rotational position signal and an ultrasonic flaw detection signal of the test body 10, are provided.