This study was carried out to examine the properties of sample amount and storage conditions on the accumulated pulsed photostimulated luminescence (PPSL) signals of soybean paste powder. Difference amounts (0.1, 0.5 and 1 g) of soybean paste powder samples stored in normal room and darkroom conditions were measured. The PPSL signals of the soybean paste powders significantly increased with irradiation dose up to 10 kGy. The PPSL signals of irradiated soybean paste powder samples decreased with increasing storage periods. The decay rates were similar to regardless of storage conditions and sample amount. The PPSL signals of the irradiated soybean paste powder measured for 120 s were higher than those measured for 60 s. These results indicated that although the PPSL signal of all soybean paste powder samples decreased with increasing storage time, detection of irradiated samples was still possible after 12 months of storage regardless of sample amount and measurement times in both normal room and darkroom conditions.