Hydrogen peroxide (H₂O₂), which is contained in industrial products, is also generated within cells. H₂O₂ causes pain but it has not been elucidated how it activates sensory neurons in the pain pathway. Here we show that transient receptor potential ankyrin 1 (TRPA1), expressed by sensory neurons in the pain pathway, is a receptor for H₂O₂. H₂O₂ activated mouse TRPA1 to induce Ca²⁺ influx and elicit non‐selective cation currents. These effects of H₂O₂ were mimicked by both reactive oxygen species and reactive nitrogen species. Cysteine‐reducing agents suppressed H₂O₂‐induced TRPA1 activation, whereas cysteine‐oxidizing agents activated TRPA1. H₂O₂ caused Ca²⁺ influx in a subset of dorsal root ganglia neurons, which responded to allyl isothiocyanate, a TRPA1 ligand. These results suggest that TRPA1 might be involved in the sensation of pain caused by H₂O₂.