The present invention provides a method and a structure for mounting a sensor substrate of a brushless motor, in which a rotation detection element is arranged near a permanent
magnet of a rotor and the sensor substrate can be securely mounted with a simple method, and thus, it is not necessary to elongate the dimension of the permanent
magnet of the rotor in an axial direction. In the present invention, insulating members that insulate a location for winding of a
stator coil from an outside are formed on a
stator core (20) on which radially arranged pole teeth (20b) are provided on an inner
peripheral surface side of the
stator core (20) with a predetermined space, a
stator coil is wound around the pole teeth via the insulating members, stopper walls (83) for preventing the coming off of the
stator coil are provided to the pole teeth of the insulating member on a
leading edge thereof, pedestal parts (84) are formed on the stopper walls (83) on an inner periphery surface side thereof, a sensor substrate (9) to which a position detection element which detects the position of a permanent
magnet (30) provided to a rotor (3) is arranged on the pedestal parts (84), locking portions for locking the sensor substrate (9) are provided to some of the pedestal parts (84), and thereby the coming off of the sensor substrate (9) in an axial direction is prevented.