A packet processing device is implemented in a network that transmits priority packets and non-priority packets having a lower priority than the priority packets. The packet processing device includes: a packet storage, a gate, a controller, a detector, a generator, and a transmitter. The packet storage stores non-priority packets. The gate is provided on an output side of the packet storage. The controller controls the gate. The detector detects a transmission pattern of the priority packets. The generator generates, based on the transmission pattern of the priority packets, a gate control signal for controlling a gate of a packet processing device implemented in another node. The transmitter transmits the gate control signal to a destination of the priority packets.