PURPOSE: To provide a reaction generating device excellent in durability, having a simple structure, and capable of giving rotational reaction to the specific operating member.

CONSTITUTION: A reaction generating device 2 is composed of an a.c. motor 6 provided with a stator around which a three-phase coil is wound, a rotor to which a permanent magnet is attached and a rotary shaft 6a extending from the center of the rotor to the outside, and wherein a steering wheel 4 for a drive game machine is fixed to its tip and a controller 8 for controlling the a.c. motor 6. The controller 8 always generates the magnetic field in the specific direction onto the stator by supplying the specific d.c. current to the three-phase coil of the a.c. motor 6. It stops the steering wheel 4 into the straight travelling state by electromagnetic attracting force to act between the magnetic field and the permanent magnet on the rotor side. When a player turns and operates the steering wheel 4, torque in the direction to return the steering wheel 4 into the straight traveling stage is generated on the rotor of the a.c. motor 6, thereby the player can enjoy the game with operational feeling like the actual vehicle.