A compiler compiling a source code and is implemented in a plurality of processor cores includes a parallel loop processing detection unit configured to detect from the source code a loop processing code for execution of an internal processing operation for a given number of repeating times, and an independent parallel loop processing code in the internal processing operation performed for each repetition to be concurrently processed, and a dynamic parallel conversion unit configured to generate a control core code for control of the number of repeating times in the parallel loop processing code and a parallel processing code for changing the number of repeating times corresponding to the control from the control core code.