Inorganic arsenic (iAs) is a food safety concern worldwide due to its high toxicity, particularly in rice, which accumulates As more easily than other crops. Accordingly, low-cost, simple methods are needed for accurate determination of iAs in food crops. We extracted total arsenic (As) from rice using HNO₃ and then reduced arsenate (As⁵⁺) to arsenite (As³⁺) using thiourea. The combined As³⁺ was separated from organic As using polystyrene resin cartridges, and quantified by hydride generation-atomic fluorescence spectrometry (HG-AFS). This method achieved 1.1 μg kg⁻¹ limit of detection, 3.6 μg kg⁻¹ limit of qualification, and <6% relative standard deviation. Validation was performed using certified reference materials and conventional high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICPMS). Compared with LC-HG-AFS or LC-ICPMS, this method appears suitable for general use because of its low cost.