To obtain an updating method capable of realizing the update of a module of a set top box with minimum data transfer quantity from a server and efficiently using a memory when the module of a set top box is updated.

When modules are arranged in a memory 11a of an STB(set top box), free areas 12a to 13c are secured between individual modules. By arranging update data 11b(+) of a module B in a free area 12b at the back of a module B (11b), it is made possible to update the modules with minimum data transfer while only a free area 12b(-) is changed without adding any other change to a memory configuration.