One partial reflecting mirror and two total reflecting mirrors being placed at one end of a resonator and three total reflecting mirrors being placed at an opposite end of the resonator are included, and the reflecting mirrors are placed so that the centers of laser light on the three reflecting mirrors placed at each end of the resonator forms a triangle. The pressing device has a balloon installed on an ultrasonic transmissionreception surface of an ultrasonic probe and presses an object to be examined by the balloon. The flat wires have a width of at least about 0.