According to an aspect of the embodiment, a system control apparatus includes a control signal transmitting unit which transmits a control signal to control circuits via first signal line. The control signal includes a command for performing a control setting on other control circuits other than own control circuit or to all control circuits. Each control circuit includes a signal receiving unit which receives the control signal transmitted from the control signal transmitting unit via the first signal line, a signal transfer unit which transfers the command included in the received control signal via second signal lines to the control circuit, and a control setting unit which performs the control setting on the own control circuit according to the command included in the received control signal or a command transferred from the other control circuits other than the own control circuit.