A mobile communication terminal 10 is assembled by a user incorporating an arbitrary desired function module 31, 32, 33 into a core module 20. When assembling the terminal, it is not possible for the core module 20 to know what type of function module is being incorporated in advance, but it is possible to ascertain the type of function module that has been incorporated by using identification information notified to the connection module control means of the core module 20 via the core module communication processing section of the function module 31, 32, 33 and the inter-module communication processing section of the core module 20. The core module 20 therefore implements a function appropriate to the users needs by appropriately controlling that function module. Therefore, it is possible to make effective use of resources, as well as reducing the burden placed on a user when upgrading or adding functions, to meet the diverse needs of the user.