An electric motor (2, 102, 201, 401) comprising: a yoke (5, 105, 208, 402) having a cylindrical section (53, 153); two pairs of permanent magnets (7, 107, 214, 404) fixed at an inner circumferential surface of the cylindrical section and disposed such that magnetic N poles and S poles are alternately disposed in a circumferential direction; an armature (6, 106, 204, 403) rotatably supported further inside in a radial direction than the permanent magnet; a plurality of brushes (130, 210, 421) configured to supply electricity to the armature; and a brush holder (22, 122, 270, 419) that holds the plurality of brushes and formed so as to be longer in one direction of the radial direction; wherein a pair of first flat sections (61, 161, 281a) opposing each other in the radial direction and a pair of arc-shaped sections (63, 163, 281b) configured to connect the pair of first flat sections are formed at the cylindrical section (53, 153), wherein the two pairs of permanent magnets (7, 107, 214, 404) are disposed respectively the arc-shaped sections (63, 163, 281b), when a width of the opposite first flat sections (61, 161, 281a) of the cylindrical section (53, 153) is represented as L1 and a width of the opposite arc-shaped sections (63, 163, 281b) is represented as R1, the width L1 of the first flat sections (61, 161, 281a) and the width R1 of the arc-shaped sections (63, 163, 281b) are set to satisfy: L1 < R1, and wherein the opposite first flat sections (61, 161, 281a) are disposed in a lateral direction of the brush holder (22, 122, 270, 419), wherein each of the first flat sections (61, 161, 281a) of the cylindrical section (53, 153) is disposed between two of the permanent magnets (7, 107, 214, 404) in the circumferential direction, wherein the portions of the arc-shaped sections (63, 163, 281b) and the first flat sections (61, 161, 281a) are alternately disposed in the circumferential direction, characterised in that each of the arc-shaped sections (63, 163, 281b) of the cylindrical section (53, 153) has a portion that is disposed between two of the permanent magnets (7, 107, 214, 404) in the circumferential direction. a yoke (5, 105, 208, 402) having a cylindrical section (53, 153); two pairs of permanent magnets (7, 107, 214, 404) fixed at an inner circumferential surface of the cylindrical section and disposed such that magnetic N poles and S poles are alternately disposed in a circumferential direction; an armature (6, 106, 204, 403) rotatably supported further inside in a radial direction than the permanent magnet; a plurality of brushes (130, 210, 421) configured to supply electricity to the armature; and a brush holder (22, 122, 270, 419) that holds the plurality of brushes and formed so as to be longer in one direction of the radial direction; wherein a pair of first flat sections (61, 161, 281a) opposing each other in the radial direction and a pair of arc-shaped sections (63, 163, 281b) configured to connect the pair of first flat sections are formed at the cylindrical section (53, 153), wherein the two pairs of permanent magnets (7, 107, 214, 404) are disposed respectively the arc-shaped sections (63, 163, 281b), when a width of the opposite first flat sections (61, 161, 281a) of the cylindrical section (53, 153) is represented as L1 and a width of the opposite arc-shaped sections (63, 163, 281b) is represented as R1, the width L1 of the first flat sections (61, 161, 281a) and the width R1 of the arc-shaped sections (63, 163, 281b) are set to satisfy: L1 < R1, and wherein the opposite first flat sections (61, 161, 281a) are disposed in a lateral direction of the brush holder (22, 122, 270, 419), L1 < R1, and wherein the opposite first flat sections (61, 161, 281a) are disposed in a lateral direction of the brush holder (22, 122, 270, 419), wherein each of the first flat sections (61, 161, 281a) of the cylindrical section (53, 153) is disposed between two of the permanent magnets (7, 107, 214, 404) in the circumferential direction, wherein the portions of the arc-shaped sections (63, 163, 281b) and the first flat sections (61, 161, 281a) are alternately disposed in the circumferential direction, characterised in that each of the arc-shaped sections (63, 163, 281b) of the cylindrical section (53, 153) has a portion that is disposed between two of the permanent magnets (7, 107, 214, 404) in the circumferential direction.