An electric motor comprising: a yoke having a cylindrical section ; two pairs of permanent magnets 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 rotatably supported further inside in a radial direction than the permanent magnet; a plurality of brushes configured to supply electricity to the armature; and a brush holder 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 opposing each other in the radial direction and a pair of arc-shaped sections configured to connect the pair of first flat sections are formed at the cylindrical section , wherein the two pairs of permanent magnets are disposed respectively the arc-shaped sections , when a width of the opposite first flat sections of the cylindrical section is represented as L1 and a width of the opposite arc-shaped sections is represented as R1, the width L1 of the first flat sections and the width R1 of the arc-shaped sections are set to satisfy: L1 < R1, and wherein the opposite first flat sections are disposed in a lateral direction of the brush holder , wherein each of the first flat sections of the cylindrical section is disposed between two of the permanent magnets in the circumferential direction, wherein the portions of the arc-shaped sections and the first flat sections are alternately disposed in the circumferential direction, characterised in that each of the arc-shaped sections of the cylindrical section has a portion that is disposed between two of the permanent magnets in the circumferential direction. a yoke having a cylindrical section ; two pairs of permanent magnets 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 rotatably supported further inside in a radial direction than the permanent magnet; a plurality of brushes configured to supply electricity to the armature; and a brush holder 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 opposing each other in the radial direction and a pair of arc-shaped sections configured to connect the pair of first flat sections are formed at the cylindrical section , wherein the two pairs of permanent magnets are disposed respectively the arc-shaped sections , when a width of the opposite first flat sections of the cylindrical section is represented as L1 and a width of the opposite arc-shaped sections is represented as R1, the width L1 of the first flat sections and the width R1 of the arc-shaped sections are set to satisfy: L1 < R1, and wherein the opposite first flat sections are disposed in a lateral direction of the brush holder , L1 < R1, and wherein the opposite first flat sections are disposed in a lateral direction of the brush holder , wherein each of the first flat sections of the cylindrical section is disposed between two of the permanent magnets in the circumferential direction, wherein the portions of the arc-shaped sections and the first flat sections are alternately disposed in the circumferential direction, characterised in that each of the arc-shaped sections of the cylindrical section has a portion that is disposed between two of the permanent magnets in the circumferential direction. <EOS>