PURPOSE: To make a transmitting output of every pulse transmission constant by changing a connected state of a current adjusting means of a load transmitting pipe by a switching means, at every transmitting pulse.

CONSTITUTION: Switching elements 6∼8 are turned on by applying a driving signal from a driving device 12, in synchronization with a transmitting trigger signal, one of them is selected, and synchronizes with a switching element 4. Variable resistors 9∼11 are adjusted so that the peak value of the corresponding pulse current becomes constant. When #1, 2 and 3 pulses in the figure are generated, an on-operation is executed in order of the elements 6, 7 and 8, together with the element 4. A charging voltage of a capacitor 2 generates a voltage drop corresponding to a value of the peak current of a current flowing to a load transmitting pipe 3, and if it is not recovered to the original voltage before the next pulse current is made to flow, and the next transmitting trigger is inputted when it is lower than the original voltage by ΔE, the current flowing to the load transmitting pipe 3 decreases in accordance with ΔE and a resistance of a discharging circuit. Accordingly, a current variation portion between transmitting pulses can be decreased by adjusting most suitably a resistance value of the variable resistors 9∼11 in accordance with the voltage variation portion ΔE.