1. A method for executing a program in a computer system including a plurality of computers which operate under different loads at different times, said computers being capable of executing a plurality of first common object codes, and at least a first one of said computers being capable of executing second object codes which are unexecutable in at least one of the other computers, wherein the method comprises the steps of: (a) compiling, by means of one of the computers, a source program into an object program comprised of: (i) a first object program section comprised of said first common object codes and corresponding to a section of the source program which is not executable by said second object codes in said first one of said computers; (ii) at least one group of second object program sections respectively to be executed by respective computers and corresponding to a same section of said source program which is executable by said second object codes by said first one of said computers, one of said second object program sections to be executed by said first computer including said second object codes for said first one of said computers; (iii) at least one third object program section which is comprised of said first object codes, and detects, at an execution of said object program by the computer system, which one of said computers is selected so as to execute said object program and selects one of said second object program sections corresponding to said detected computer; (b) selecting, one of said computers which is to execute the object program, by means of execution of a scheduling program preloaded in a predetermined one of said computers; and (c) executing said object program by said selected computer, whereby said first and third object program sections and one of said second object program sections corresponding to said selected computer are executed; wherein said selection of said selected computer for executing said object program is effected such that one of said computers which has a load lower than any other of said computers in the system is selected.