PURPOSE: To obtain a small-sized, light-weight transmitter of excellent acoustic radiation efficiency, by employing a non-active column material of both large rigidity and strength and forming a first step displacement enlargement mechanism by the small hinges and 2 1- stage displacement enlargement mechanism coming out from 2 pieces of small hinges and each non-active column material.

CONSTITUTION: In order that a small hinge 23 makes the moment of rotation large given to a first step lever 23, the comparative rigidity is large against the vertical displacement, and is designed so that a lever 24 is easy to turn and displacement easy. Further, the displacement enlarged in an output point of a first step lever is transmitted to a long hinge 26, and with the long hinge 26' protruding from a pedestal 25 with this, a second stage control is turned. Hereupon, since the angle of rotation of a second step lever since the vertical displacement output from the first step lever 24 becomes a few times the vertical displacement output from an active column-shaped form 21, it becomes a few times the angle of rotation of the first step lever 24. The vertical displacement output from the second step cover drivers a piston acoustic radiation matter 29 with sharp increase.