A permanent magnet motor, comprising: an armature; a rotor; and an angle detector, wherein the armature includes: an armature iron core; and an armature winding, wherein the rotor includes: a rotor iron core; and a permanent magnet wherein the angle detector includes: a sensor magnet; and a semiconductor sensor, wherein the rotor iron core including the permanent magnet is fixed to a rotation shaft, the rotation shaft being held in an extension direction of the rotation shaft of a frame via bearings (16, 17); wherein the sensor magnet is magnetized into two poles and is provided in an end portion of the rotation shaft, and has the same rotation center as a rotation center of the rotation shaft, wherein the semiconductor sensor is opposed to the sensor magnet in an extension direction of the rotation shaft; wherein the semiconductor sensor and the sensor magnet have a gap formed therebetween, and wherein a plate member constructed of a thin plate made of a magnetic substance is provided between the semiconductor sensor and an end portion of the armature iron core on the semiconductor sensor side; the plate member being separate from a section of the frame positioned between the angle detector and the armature iron core in an axial direction; characterized in that the plate member includes a first section extending in the axial direction and a second section extending in an imaginary plane perpendicular to the axial direction, wherein the first section extends from the armature iron core in the axial direction so as to be away from the armature iron core. an armature; a rotor; and an angle detector, wherein the armature includes: an armature iron core; and an armature winding, an armature iron core; and an armature winding, wherein the rotor includes: a rotor iron core; and a permanent magnet a rotor iron core; and a permanent magnet wherein the angle detector includes: a sensor magnet; and a semiconductor sensor, a sensor magnet; and a semiconductor sensor, wherein the rotor iron core including the permanent magnet is fixed to a rotation shaft, the rotation shaft being held in an extension direction of the rotation shaft of a frame via bearings (16, 17); wherein the sensor magnet is magnetized into two poles and is provided in an end portion of the rotation shaft, and has the same rotation center as a rotation center of the rotation shaft, wherein the semiconductor sensor is opposed to the sensor magnet in an extension direction of the rotation shaft; wherein the semiconductor sensor and the sensor magnet have a gap formed therebetween, and wherein a plate member constructed of a thin plate made of a magnetic substance is provided between the semiconductor sensor and an end portion of the armature iron core on the semiconductor sensor side; the plate member being separate from a section of the frame positioned between the angle detector and the armature iron core in an axial direction; characterized in that the plate member includes a first section extending in the axial direction and a second section extending in an imaginary plane perpendicular to the axial direction, wherein the first section extends from the armature iron core in the axial direction so as to be away from the armature iron core.