To provide a packet generating device that improves a packet processing efficiency with a simple configuration.

The packet generating device 10 that generates a 2nd packet with a packet length shorter than a length of a 1st packet from a data string consisting of consecutive 1st packets is provided with a packet division means 17 that divides the 1st packet into the 2nd packet and adds a succeeding 1st packet to a tag end part of the 1st packet in the case that a data length of the 1st packet in the 2nd packet including the tag end part of the 1st packet is less than a payload length of the 2nd packet and with a head position information addition means 13 that adds head position information denoting a head position of the 1st packet in the 2nd packet to a prescribed area of the 2nd packet in the case that the 2nd packet includes the head part of the 1st packet.