PURPOSE: To allow the direction of a sound wave beam not to be changed even when an under water transmitting equipment is inclined from a prescribed posture.

CONSTITUTION: An inclination sensor 1 is provided on the under water transmitting equipment, an echo sounder transmitter 5 is made to be a phased array type consisting of plural trasducer devices 5-1 to 5-N and phase shifters 3-1 to 3-N are provided corresponding to signals supplied to respective transducer devices 5-1 to 5-N. Then. when the inclination sensor 1 detects the inclination of θ, phases of exciting signals to be impressed on respective transducer devices 5-1 to 5-N are controlled by generating phase shift control signals so that the direction of the sound wave beam is inclined by -θ from a prescribed direction and by supplying them to phase shifters 3-1 to 3-N.