Provided is a high-productivity method for producing an interdental brush which is hard to bend even after repetitive bending during use and is not likely to give pain when inserted between teeth. Also provided is an interdental brush. The method for producing an interdental brush comprises a step for molding the primary molding of a brush portion (2) by mold clamping first and second dies constituting a cavity (S1) having a shape corresponding to the shape of the brush portion (2) and then by filling the cavity (S1) with injected first resin, a step for molding the secondary molding of a handle portion (3) where the proximal portion (2a) of the brush portion (2) is embedded by mold clamping with respect to the first die a third die constituting a cavity (S2) having a shape corresponding to the shape of the handle portion (3) and then filling the cavity (S2) with injected second resin after mold opening the second die with respect to the first die and mold releasing the proximal portion (2a) of the brush portion (2) from the second die and a step for mold releasing the two-color molding of an interdental brush, consisting of the brush portion (2) and the handle portion (3) molded integrally, from the first and third dies.