In the present invention, in order that a busy judgment of a register can be made without fail and without increasing the number of hardware resources for storing a request into the register provided at the final stage of a pipeline register in a stage in which the request is retained halfway in the pipeline register in a pipeline processor, a first counter for counting the number of valid requests in the registers between a judgment section interposed in the pipeline register and for judging whether the request is a valid request and a request queue and a busy judgment section for judging whether the request queue is in a busy state based on the number of valid requests counted by the first counter are provided and a judgment is made by the judgment section based on the result of the busy state judgment by the busy judgment section.