A method of managing IP addresses in a device performing communication using the IP address includes acquiring IP addresses by a plurality of methods; storing the plurality of IP addresses such that the methods are discernable when the plurality of acquired IP addresses are the same, determining an effective IP address used in the communication from the plurality of IP addresses according to predetermined priority in the methods, and setting the IP address to be used in the communication; and determining the valid IP address according to the priority from the stored IP addresses except for the disappearing IP address when the set IP address disappears, and setting the IP address to be used in the communication.