PURPOSE: To automatically check whether an instruction to access a memory or a register to be used while switching a bank uses the bank to be used for designing a program or not.

CONSTITUTION: A source program 3 contains descriptions concerning a bank name 32 to be used for designing the program concerning each instruction, a language processing program 1 inputs the source program 3 and generates an object file 41 containing a bank name 42 having the same contents as an object code 41 and the bank name 32, a debugger 2 inputs the object file 4 and prepares a correspondent table 5 in the form of the bank name 52 having the same contents as the bank name 42 corresponding to an address 51, the bank name to be actually used is fetched from a bank holding area 81 in the case of executing the instruction, and it is compared whether the fetched bank name is coincident with the bank name 52 in the correspondent table or not.