The invention relates to an interdental brush. The interdental brush comprises a long and narrow handheld rod. A row of multi-bundle bristles are implanted on the front side or the back side of the head part of the long and narrow handheld rod. According to the interdental brush, the bristles arranged in one row are arranged to achieve cleaning of gaps between teeth, and bristles can be arranged on the front surface or the back surface or at the front end to be convenient for a user to use and meet cleaning requirements of different modes and different parts. Particularly, it is worth mentioning that the two groups of inclined bristles are used, and wedge shapes are formed on the tops of the bristles through trimming. The wedge shapes make the flexible bristles stretch into the gaps between the teeth, and relatively wide bottom root parts can better clean adjacent tooth side faces in the gaps between the teeth. The problems are solved that wide bristles cannot easily enter the gaps between the teeth, and narrow bristles can easily enter the gaps between the teeth but cannot easily clean the adjacent tooth side faces in the gaps between the teeth.