A semiconductor device includes a common resource commonly used by plural processes executed on a processor, a semaphore controlling the possessory right of the common resource, and a semaphore management unit performing a process of acquiring the possessory right of the common resource to the semaphore in response to a request of a process performed on the processor. When a request to acquire the possessory right of the common resource is received from a first process in the plural processes and the possessory right cannot be obtained, the semaphore management unit switches the process executed on the processor to a second process, repeatedly performs a process of acquiring the possessory right requested by the first process to the semaphore and, when the possessory right requested by the first process is obtained, switches the process on the processor from the second process to the first process.