A method of manufacturing a magneto field type motor, the motor having a plurality of main magnetic poles made of permanent magnets that are arranged to the inner circumference of a yoke at equal intervals; a plurality of auxiliary poles made of magnetic materials that are arranged to adjoin the increasing magnetic flux sides of the main magnetic poles; and a plurality of magnet holding springs that are arranged between the auxiliary poles and the decreasing magnetic flux sides of the main magnetic poles; each magnetic holding spring being provided in a "]"-like sectional shape having a back-plate fixed to an inner circumference of the yoke and a pair of side-plates (31, 32) extending in a direction of a center of the yoke from both sides of the back-plate; the method comprising the consecutive steps of: for each magnet holding spring, forming a pair of nail-plate portions on one side-plate of the magnet holding spring when it is still deployed as a flat plate, the pair of nail-plate portions regulating the position of the main magnetic pole in the axial direction of the yoke once the magneto field type motor is assembled; forming sub-assemblies, each sub-assembly having a magnet holding spring and an auxiliary pole, by attaching an auxiliary pole beforehand to the side-plate of the magnet holding spring not having the nail-plate portions in a stage where the magnet holding spring is still deployed as a flat plate before the back-plate and the pair of side-plates (31, 32) are bent into the "]"-like sectional shape, the magnet holding spring and the auxiliary pole being integrally attached by press fitting a concave part provided in either one of the side-plate or the auxiliary pole with a convex part provided in the auxiliary pole or the side-plate respectively, and by bending the magnet holding spring into the "]"-like sectional shape; fixing the sub-assemblies to the inner circumference of the yoke such that magnet insertion spaces are formed between adjoining sub-assemblies; from the axial direction of the yoke, inserting the main magnetic poles in the magnet insertion spaces to thereby fix the main magnetic poles and the auxiliary poles by pressing them together in the circumferential direction of the yoke by the elasticity of the magnet holding springs; and bending and extending the pairs of nail-plate portions of each of the magnet holding springs towards the main magnet poles. for each magnet holding spring, forming a pair of nail-plate portions on one side-plate of the magnet holding spring when it is still deployed as a flat plate, the pair of nail-plate portions regulating the position of the main magnetic pole in the axial direction of the yoke once the magneto field type motor is assembled; forming sub-assemblies, each sub-assembly having a magnet holding spring and an auxiliary pole, by attaching an auxiliary pole beforehand to the side-plate of the magnet holding spring not having the nail-plate portions in a stage where the magnet holding spring is still deployed as a flat plate before the back-plate and the pair of side-plates (31, 32) are bent into the "]"-like sectional shape, the magnet holding spring and the auxiliary pole being integrally attached by press fitting a concave part provided in either one of the side-plate or the auxiliary pole with a convex part provided in the auxiliary pole or the side-plate respectively, and by bending the magnet holding spring into the "]"-like sectional shape; fixing the sub-assemblies to the inner circumference of the yoke such that magnet insertion spaces are formed between adjoining sub-assemblies; from the axial direction of the yoke, inserting the main magnetic poles in the magnet insertion spaces to thereby fix the main magnetic poles and the auxiliary poles by pressing them together in the circumferential direction of the yoke by the elasticity of the magnet holding springs; and bending and extending the pairs of nail-plate portions of each of the magnet holding springs towards the main magnet poles.