To achieve hygienic dental treatments by keeping the head parts of instruments, used by operators in the dental treatments, immersed in a chemical liquid during the unuse period thereof.

A dental instrument holder 3 has a hand piece part carrier part 3a where the handpiece parts 4a of the instruments 4 for dental treatment are placed and a liquid bath part 3b following the handpiece part carrier part 3a. When the handpiece parts 4a of the instruments 4 are placed on the handpiece part carrier part 3a, the blades 9 mounted on the head parts 4a of the instruments 4 and/or the head parts 4a are immersed into the chemical of the liquid bath.