An optical packet switching device causes branching of an optical packet that is input to an optical switch and detects a synchronization pattern having a predetermined number of bits from the branched optical packet. Then, the optical packet switching device calculates a synchronization point indicating a location of the synchronization pattern with respect to a detection timing and controls, in accordance with the calculated synchronization point, a delay amount of a delay element that delays an optical packet ON signal that is output to the optical switch.