A carbon brush holder includes an insulated housing having a through hole with a first section, a second section and a stepped portion between the first and second sections. A carbon brush-holding member is inserted into the first section of the insulated housing and has a first end face, a second end face opposite to the first end face, and an insertion portion adjoined with the second end face. The insertion portion of the carbon brush-holding member extends into the second section of the insulated housing, thereby enabling the second end face of the carbon brush-holding member to be located in the second section of the insulated housing. Thus, the second end face of the carbon brush-holding member can firmly contact a conductive member that is disposed inside the second section of the insulated housing and electrically connected with a carbon brush inserted into the carbon brush-holding member.