To provide a oral hygiene device for capable of treating easily at a desired place and being suitable for mass production.

The disposable toothbrush consists of a tank section 2a which has a hollow cavity accepting the treatment fluid and a fluid outlet 24 on an outlet stabilizer 26 and a treatment section 2b which has a brush 4, a cover cap 23 and a treatment head 3 that is put on the tank section 2a when it is not used. It connects the tank section 2a with the treatment section 2b to form the connection for fluid between the hollow cavity and the opening of the fluid outlet 24. Pushing the tank section 2, the fluid flows from the hollow cavity through the fluid outlet 24 to the opening of the outlet 29. The cover cap 23 closes the fluid outlet 24 of the tank section 2a at a setting state to cover the treatment head 3.