To solve such problems that conventional toothbrushes need to be discarded and incinerated as refuse after use, and as a result, a waste of resources are caused and carbon dioxide is produced.

A toothbrush is provided separately with: a cylindrical toothbrush portion for attaching a replaceable toothbrush portion, the cylindrical portion being provided with an uneven portion to prevent an end part of the toothbrush from swinging in a right and left direction when the cylindrical portion is fitted to the end part of the toothbrush handle; and the replaceable toothbrush portion. Thus, after an appropriate period of use, the replaceable toothbrush can be easily replaced. In the toothbrush, the toothbrush handle can be repeatedly used, and the toothbrush significantly contributes to the reduction of carbon dioxide, in addition to the reduction of refuse.