Abstract: A transmission apparatus is a transmission apparatus that generates a pressure wave for transmitting data in drilling mud, and includes a tubular member, a plurality of valves that are provided side by side in an axial direction of the tubular member inside the tubular member, each of which includes a stator including holes for passing the drilling mud, and a rotatable rotor which is provided to overlap the stator and includes blocking portions blocking the holes in the stator according to a rotation position, a motor that rotates the respective rotors, and a control unit that controls the motor 130 so as to rotate and stop the respective rotors at frequencies different from each other, according to data to be transmitted.