An information processing device for causing a processor to execute a plurality of threads by switching between them. Each thread performs a process in correspondence with an obtainment of an event. The information processing device, when causing a second thread to transit from a non-execution state to an execution state to replace a first thread, detects whether or not, in the first thread having transited to the non-execution state, a next start position of a process belongs to an already processed part, detects whether or not a start position of a process in the second thread in the execution state belongs to the processed part; and determines whether or not to set a context for execution of the second thread into the processor in accordance with detection results of the first and second detection units, and performs processing in accordance with the determination.