We report a case of contact dermatitis due to sodium bisulfite in Tathion eye drops. A 72-year-old woman was treated daily with two solutions including Tathion eye drops for senile cataract for two years and three months. She developed edema, swelling, erythema, and vesicles on her eyelids. Because contact dermatitis due to a topical medication was suspected, patch testing was performed after disappearance of her eruption. A positive reaction to sodium bisulfite in Tathion eye drops was confirmed. Therefore, we diagnosed her eruption as contact dermatitis due to sodium bisulfite. The reaction to sodium sulfite in the next patch testing was negative. To the best of our knowledge, this is the first report from Japan about contact dermatitis caused by this medication.