Abstract: This invention relates to a semi-automatic gas cutting machine which is capable of being operated with one hand freely. More particularly, it relates to a gas cutting machine which enables the steel cutting by: mounting in combination with a controlling apparatus which controls a motor and the rotation thereof, a transmission axis having a first gear at the top and being capable of transmitting the rotation of said motor, a second gear mounted so as to engage with said first gear and rotate around a device head freely, and a driving wheel which is capable of rotation by contacting the outer periphery thereof with said second gear around the device head respectively; and travelling the device head and a cutting nozzle attached to it by the rotation of a driving wheel at the gas cutting.