The optimum conditions of preheat temperature, stimulation temperature, etc. in the single-aliquot regenerative optically stimulated luminescence (SAR OSL) method were examined specifically for measuring background dose in natural quartz extracted from soils collected around Tokai-mura in Japan. The objective was to assess the potential of SAR-OSL dosimetry using soils for retrospective assessment of a radiation accident. Variation in dose with depth was also measured. The SAR data showed good reproducibility and dose recovery, and there was no evidence of fading of the quartz signal based on “delayed” dose recovery experiments. The minimum detection limit (MDL) dose was about 0.1 Gy. The dose dependence was measured using both the above SAR OSL protocol as well as a SAR thermoluminescence (TL, violet emission) protocol. The background doses were generally in the range of the MDL to several Gy, and no clear trend in dose depth profile was observed. From these results, we conclude that SAR OSL dosimetry using natural quartz extracted from soil could be used to evaluate the dose of an accident.