This paper presents findings of an explosion risk evaluation study to obtain basic data concerning the sympathetic detonation of munitions for safe treatment of munitions. Trinitrotoluene (TNT) was used as a standard explosive and model munitions of 155 mm in diameter were exploded in the field experiment. The static overpressure of blast waves were measured by 6 piezoelectric gages located at between 10 m and 100 m. From the blast data, blast wave parameters (peak overpressure, time of arrival, duration and positive impulse) were obtained and TNT equivalent masses of munition(s) were estimated based on the peak static overpressure and positive impulse. Results showed that sympathetic detonation occurred up to 17 munitions. Moreover, the TNT equivalent mass increased with distance. This tendency may be due to the slow burning of TNT in the acceptor munitions.