To achieve the speedup of flaw detection processing by certainly suppressing the effect of an ultrasonic echo formed in a group just before set as a control target.

An ultrasonic flaw detection device has an array probe with a plurality of ultrasonic vibrators arranged in one direction, a pulser for output of excitation pulses for exciting the ultrasonic vibrators, a receiving unit for acquiring the output corresponding to the intensity of the ultrasonic echo received by the ultrasonic vibrators to output the same as an echo signal, and a control unit for controlling the output of the excitation pulses by the pulser and forming the data related to the damage of an inspection target from the intensity of the echo signal. A main control unit controls the output of the excitation pulses and the reception of the echo signal in the unit of the group (#a-#g) constituted by a plurality of the ultrasonic vibrators. At this point, the group separated from the group in a cycle just before set as the control target at a predetermined interval or above is set to a next control target.