To provide a rotary machine which has a high space factor for armature coils and therefore can be manufactured at low cost.

This rotary machine has a ring-shaped armature core 1 which is made by laminating thin steel plates, teeth 2 which project on the inside of the armature core 1 at equal intervals in the circumferential direction, armature coils 4 which are concentratedly wound around the teeth, and bobbins 5 which are installed in slots 3 formed between each two adjacent teeth 2 and which store armature coils 4. A bottom face 31 of each slot 3 is constituted of two flat faces 11a, 11b which extend from the roots of the adjacent teeth 2a, 2b toward the center of the core and are vertical to the center lines of the teeth 2a, 2b which the flat faces abut against. About the bobbins 5, bobbins 5a having a trapezoidal cross section and bobbins 5b having a rectangular cross section are located alternately in the circumferential direction.