1. A method of controlling the execution of a control program known as an operating system for controlling the execution of user's programs in a multi-processor system having a plurality of processors and a memory for storing said control program and said user's programs to be executed by each of said processors, said control program and said user's programs including operating system process execution instructions for initiating operating system control, said memory being connected to said plurality of processors for use in common therewith, said control program being divided into a plurality of subprograms which are concurrently executable to perform respective operating system processes and said memory further storing supervising data including status data prepared for each of said operating system processes, said method comprising: a first step in which, when a given operating system process execution instruction contained in said user's programs or said control program is executed in any of said processors, the status data in said memory corresponding to the operating system process designated by said operating system process execution instruction is changed from wait-state data to ready-state data; a second step in which, when any one of said processors is executing one of said user's programs, such processor intermittently interrupts the execution of the user's program to read out from said memory said status data and to detect the presence of the ready-state data relating to any operating system process; a third step in which when said ready-state data relating to an operating state process is present and detected, any of said processors detecting said ready-state data executes the ready-state operating system process relating thereto, while any of said processors which detect no ready-state data resumes executing the interrupted user's program; and a fourth step in which, when the execution of a ready-state operating system process is completed by a processor, that processor executing said ready-state operating system process again reads out from said memory said status data to detect the presence of other ready-state data relating to another ready-state operating system process.