A plurality of operation units connected in a pipeline structure performs an operation processing on data. A process control unit operates in synchronization with a system clock signal and generates a process control signal for controlling the operation units upon receiving a data notification signal that notifies the process control unit of an arrival of data from outside. A clock-control signal generating unit operates in synchronization with the system clock signal and generates a clock control signal for controlling a clock supply to each of the operation units upon receiving the process control signal.