<p>In order to provide a self-propelled cable relay truck capable of preventing cable damage: a power-supply-side cable (65) for transmitting power between an external power supply (60) and a relay truck (30), which functions as the self-propelled cable relay truck, and a shovel-side cable (66) for transmitting power between the relay truck (30) and an electric work shovel (1) are connected to the relay truck (30); and the relay truck (30) is provided with a power transmission relay (32)for relaying power between the power-supply-side cable (65) and the shovel-side cable (66); a travel apparatus (40) for carrying out a travel operation so as to be able to move a power control unit (32); and a movement control unit (51) for controlling the movement of the travel apparatus (40).</p>