When a specified task process may mix with another more highly prioritized task process, it is aimed at accurately calculating a process time for the specified task process. A CPU 11 can simultaneously perform a plurality of task processes such as a task process to display the reproduction time during an audio reproduction process on a display 20 and a task process concerning a telephone call. A DSP 12 performs the audio reproduction process and changes a timing to notify the CPU 11 of information about the audio reproduction time in accordance with loads on the task process in the CPU 11.