PURPOSE: To automatically check the deterioration of performance in the execution of a compiler without depending on a manual operation by comparing respective compiled results from an analysis result obtained from plural compiled results.

CONSTITUTION: An object code obtained by compiling one source program 100 by a debugged compiler 101 and a compiler 103 with use results or an intermediate code including object code information or an object list are inputted. Input is divided (106) into blocks and the number of instructions, the idle time of a pipe line and execution time including the idle time of the pipe line are obtained for respective blocks. Information obtained from plural compilers 101 and 103 are compared (111) or a DO loop is detected (107) from input and information on the DO loop, which is obtained from information on respective blocks constituting the DO loop are compared and a compared result 112 is outputted. Thus, a bug and a place where there is the deterioration of performance in execution can automatically and speedily be detected at the time of compiling.