1. A synchronization method executed by a multi-core processor system, the synchronization method comprising: registering based on a synchronous command issued from a first CPU, a plurality of CPUs to be synchronized and a count of the CPUs into a specific table; counting by each of the CPUs and based on a synchronous signal from the first CPU, an arrival count for a synchronous point, and creating by each of the CPUs, a second shared memory area that is a duplication of a first shared memory area accessed by processes executed by the CPUs; and comparing the first shared memory area and the second shared memory area when the arrival count becomes equal to the count of the CPUs, and based on a result of the comparison, judging the processes executed by the CPUs.