An immersion type automatic ultrasonic testing apparatus for detecting flaws of balls comprising a tank for containing a liquid medium of transmitting ultrasonic wave, a ball rotating device for rotating a ball to be tested, an ultrasonic flaws detection device for detecting surface flaws in the ball while swiveling a probe around the ball rotated by the ball rotating device or rotating the ball spirally by the ball rotating device with or without swiveling the probe, and a ball feeding device for feeding the ball to the position of the ball rotating device. The ball feeding device comprises an air cylinder for holding the ball by suction at the tip thereof. For the suction holding of the ball at the tip of the air cylinder, a level regulating device is additionally provided for setting a level of the liquid medium of transmitting ultrasonic wave in the tank wherein the ball rotating device and the ultrasonic flaws detection device are placed.