In a printing apparatus on a DHCP network, printing data accumulated in the printing apparatus is deleted without troubling a user and shortage of storage capacity is prevented. The printing apparatus is connected through a network to a DHCP server apparatus that stores IP address assignment information including an IP address of each DHCP client. The printing apparatus includes a printing data storage portion that accumulates printing data transmitted from each DHCP client along with the IP address of each DHCP client, and a CPU that determines whether or not each DHCP client is invalid based on IP address lease information stored in the DHCP server and deletes the printing data of the DHCP client which is determined to be invalid from the printing data storage portion.