Objectives: The purpose of this research was to develop a method for monitoring personal exposure to benzyl violet 4B (BV) and direct blue 15 (DB) in workplace air for risk assessment. Methods: We evaluated the utility of the proposed method by examining the following: recovery; method limit of quantification; reproducibility; and storage stability of the samples. Results: An air sampling cassette containing a glass fiber filter was chosen as the sampler. BV and DB were extracted from the sampler filters with a solution of water and methanol (7:3, v/v) and then analyzed by a high-performance liquid chromatograph equipped with a photo-diode array detector. The overall recoveries from spiked samplers were 94-102% and 94-99% for BV and DB, respectively. The recovery after seven days of storage at 4°C exceeded 95%. The method limits of quantification were 0.250 and 1.25 μg/sample for BV and DB, respectively. The relative standard deviations, which represent the overall reproducibility defined as precision, were 0.6-4.1% and 0.8-2.9% for BV and DB, respectively. Conclusions: The proposed method enables 4 h personal exposure monitoring of BV and DB at concentrations of 1-2,000 μg/m³ for BV and 5-2,000 μg/m³ for DB, with a 240 l sampling. Thus, the proposed method is useful for estimating worker exposure to BV and DB.