An optical packet switch device includes an optical switch control section and an optical switch section. The optical switch control section includes a synchronization pattern detecting unit which detects a frame synchronization pattern from a parallel data signal and detects a delay bit number showing that the frame synchronization pattern is stored at a position shifted by how many bits from the first bit of the parallel data signal, a header analysis unit which analyzes a header and detects an optical packet length and route information of an optical packet signal, and an output competition determining unit which determines passing/discarding of the optical packet signals competing with each other based on the optical packet length and the route information detected by the header analysis unit and delay bit number information detected by the synchronization pattern detecting unit.