Parallelization compile method and system

In order to make parallel processing of a serial execution type user program automatically and at a high speed without re-coding, an object code is parallelized by detection of the possibility of parallel execution in an iteration unit of a loop, detection of the possibility of parallel execution of each statement in the loop, the interchange of an outer loop by an inner loop of a multiple loop, reduction of the multiple loop to a single loop, inclined coversion for making parallel execution along a wave front plane (line) when sufficient multiplicity is not derived, and the program which is estimated to have the shortest processing time is selected from the granularity, and multiplicity of the object code, the variance of the number of instructions and the proportion of synchronization control at the time of parallelization of the object code.