To provide a method for manufacturing a brush, in which orientational performance of bristle tufts is so good that the bristles are neatly arranged.

The method includes a step of introducing bristles of a predetermined length into an introducing hole of a sleeve, and feeding the introduced bristles out of the introducing hole to be introduced into a bristle tuft inserting hole of a bristle tuft holder through a bristle installation hole at a bristle installation base part. For feeding the bristles out of the sleeve, a push pin which can be inserted into the sleeve is used. The push pin includes a part L4 having a sectional form corresponding to a cross-section of the introducing hole of the sleeve, and a tip part which corresponds to the form of a tip of the bristle tuft inserting hole. Hole diameter of the bristle tuft inserting hole is set larger than hole diameter of a bristle hole of a brush body. As/Ai ratio in the sleeve is 1.02-1.3. After the bristles are introduced into the sleeve at a bristle density of 47-75%, the introduced bristles are fed out of the sleeve, so that they are inserted into the bristle hole at a bristle density of 60-80%.