The present invention provides a rotary electric machine, in which it is possible to reduce the dimension of a casing in a direction along a rotation center line. The rotary electric machine comprises a magnet rotor 2 rotating about a rotation center line 1 and one or more magnetic sensors 11 for detecting leakage flux leaking out of the magnet rotor 2. The magnet rotor 2 and a stator 3 are received in a casing 4. A sensor receiving portion 12 for receiving the one or more magnetic sensors 11 is disposed in an outer wall portion of a side wall of the casing 4 located in an extending direction of the rotation center line 1 of the magnet rotor 2. The one or more magnetic sensors 11 are received in the sensor receiving portion 12. The sensor receiving portion 12 is disposed in a position that allows the one or more sensors to detect leakage flux leaking out of the magnet rotor 2.