An information processing system includes a processing unit which executes a prefetch instruction included as one of a plurality of instructions of a program in a main memory two hierarchical level caches connected to the processing unit and the main memory as arranged so that a primary cache close to the processing unit is a first level cache, and a secondary cache close to the main memory is a second level cache. The prefetch instruction, when executed, causes the processing unit to perform a prefetch operation by transferring operand data to be used in a subsequent load instruction from the main memory to the two hierarchical level data caches, prior to executing the subsequent load instruction. The prefetch instruction includes a plurality of indication bits for specifying cache levels to which the operand data is to be transferred.