PURPOSE: To freely extend the size of a patch area without preparing the patch area in advance by automatically extending and allocating the patch area for each module.

CONSTITUTION: A link control sentence input processing means 8 to prepare a control sentence information table 3 based on an inputted link control sentence 1, and a link processing means 7 to link a program while referring to the control sentence information table 3 are provided. When the size of the patch area is instructed by an additional link control sentence 2 for the unit of a module, the link processing means 7 extends and allocates the patch area for each module based on this size. Namely, since the patch area is automatically extended and allocated for each module, the module can be branched to the patch area without address constant. Thus, concerning the module without the patch area or the module lacking the patch area, the patch area can be easily extended only by linking again.