A plurality of ultrasonic flaw detection methods can be switched and executed by a simple operation. An ultrasonic flaw detection apparatus includes a switching circuit 3 for permitting an angle probe 1 and a normal probe 2 to be arbitrarily switched to a transmission unit T and a reception unit R of a flaw detector. The switching circuit 3 can select an angle flaw detection mode for transmittingand receiving an ultrasonic beam only by the angle probe, an SPOD mode for transmitting the ultrasonic beam by the angle probe and receiving a diffracted wave by the normal probe, a flaw detection mode executed by a combination of angle flaw detection mode the SPOD method for transmitting the ultrasonic beam by the angle probe and receiving a reflected wave by the angle probe as well as receivingthe diffracted wave by the normal probe, and a normal flaw detection mode for transmitting and receiving the ultrasonic beam by the normal probe.