A compact data acquisition system in use for a geomagnetic pulsation study has been constructed. The system is composed of a data processing system controlled by a microprocessor, cassette tape recorder, chronometer and short wave radio receiver. The system is programmed to calibrate the chronometer every five minutes by receiving a standard time signal, such as JJY (Japan), WWV (USA) and so on. The system improves a signal to noise ratio of the radio waves by signal stacking processes to minimize errors in the chronometer calibration. Even in a very weak signal, the system can discriminate a second pulse. The calibration accuracy is 10msec, including circuit signal delay when a radio propagation delay is neglected. The system is programmed to sample three component magnetometer signals at intervals of 3 sec and can store 1.3 Mbytes of data in a C-90 cassette tape which is equivalent to ten-day data. The system is suited for an unmanned operation at a station remote from the standard signal station.