A synchronous controller is formed with a cycle master module and one or more control modules doubly connected through a synchronous bus and an event bus. The event bus is used for transmitting data with a larger volume. The control modules each cyclically carry out execution of a user program for controlling an object apparatus to be controlled. The cycle master module exchanges data with the control modules through the event bus and the synchronous bus. Each of the control modules carries out one cycle of the execution of the user program by using reception of synchronous data transmitted from the cycle master module through the synchronous bus as a trigger.