An ECU includes a plurality of motor driving circuits for driving at least one motor, a plurality of computers and a plurality of clock circuits. A first computer, which is at a synchronization signal transmission-side, transmits a synchronization signal to a second computer, which is at a synchronization signal reception-side. The first computer and the second computer execute a plurality of specific periodic processes, which are processes executed at cycle periods (for example, 200 μs, 400 μs) of different natural number multiples of a cycle period (for example, 200 μs) of the synchronization signal and need be synchronized. Each timing of the plurality of specific periodic processes is determined based on one synchronization signal.