Abstract: A timer device for gas stove for allowing gas turning-off automatically, which comprising a housing, a disc-like wheel, a motor, a driving wheel, an microswitch and a timing circuit, wherein the housing mounted on a surface of a gas stove, an top surface and a bottom of the housing respectively defined with an upper and a lower round holes for the passage of a rotary-knob switch, about the periphery of the upper round hole formed with a plurality of locating holes for the insertion of locating wheels, the locating wheels being “V”-shaped in its cross section for supporting the disc-like wheel, the disc-like wheel mounted under the upper round hole, at the center of the which an oblong aperture is formed and at the periphery of the bottom of the wheel provided with teeth for engaging with the driving wheel of the motor, a protrusion upstanding from the disc-like wheel; the motor disposed in the housing, with the cooperation of the prior mentioned elements, when the gas is being used, a normal contacting pole i