1. A computer readable recording medium for storing a computer program executed by a computer, the computer having a hybrid operating system including a general purpose operating system (GPOS) and a real time operating system (RTOS), the RTOS executing a process under the GPOS as one of real time tasks (RT tasks) to execute the process with a high priority, the computer executes the GPOS as a general-purpose OS task (GP task), the computer program making a computer execute: transmitting a request for a communication between the RTOS and the GPOS from an RT task having a priority and included in the RT tasks to the GP task; setting the RT tasks in a wait state, when the communication between the RTOS and the GPOS is requested; determining whether the priority of the RT task requesting the communication is the highest in the RT tasks being set in a wait state; and making the GP task succeed to the priority of the RT task requesting the communication and being determined to have the highest priority in the RT tasks being set in the wait state; resuming execution of the RT tasks being set in the wait state in the setting step, by ending the communication; determining whether an other RT task having the highest priority is present in the RT tasks being set in the wait state, by requesting a communication between the RTOS and the GPOS, by using a priority succession management list in which task control blocks of all RT tasks being set in the wait state are connected in order of priority; and when presence of the other RT task having the highest priority is determined by specifying a head of the priority succession management list, making the other RT task succeed to priority of the RT task having the highest-priority.