We report 7 cases of chemical burns due to hydrofluoric acid (HF). The patients suffered from severe pain. However, the pain was relieved after treatment with calcium gluconate. 6 out of the 7 cases were men. At the accidental exposures, all the patients had been engaged in washing or cleaning work and received burns on their hands and/or fingers. In one case, the forearm was also involved. During such work, all the patients had used rubber gloves, but the gloves had pinholes. For the treatments, 4% calcium gluconate jelly was applied in 5 cases and 4 of 7 were subcutaneously injected with 8.5% calcium gluconate. The involved nails were removed in 5 cases. It is concluded that physicians should provide calcium gluconate jelly and subcutaneous injections to treat an HF burn and should not hesitate to remove the involved nails. To prevent chemical burn due to HF, education and reeducation of workers regarding the hazard of this chemical are necessary.