A command apparatus (10) for a plurality of laser power supplies (11, 12) comprises: a command generating section (5) generating commands for the laser power supplies; and a separating section (36) separating the generated commands into a bias command, an output command, an offset command and a gain command, wherein the bias command and the output command are common to the laser power supplies, the offset command and the gain command are defined at least in accordance with the discharge tubes corresponding to the laser power supplies respectively, wherein the command apparatus further comprises a transmitting section (37) transmitting, to the laser power supplies, the bias and the output command which are common to the laser power supplies and, transmitting the offset and the gain command defined at least in accordance with the discharge tubes corresponding to the laser power supplies respectively, corresponding to the laser power supplies.