A gas cooktop includes a cooktop body having a burner head which when activated generates a fire for heating cookware placed on the burner head, and a control system which includes a fire detection apparatus installed over the burner head and is aligned with the burner head. The control system further includes a control apparatus receiving a signal of the fire detection apparatus to control the fire of the burner head. The control apparatus determines, depending on whether the fire detection apparatus detects the fire of the burner head, whether cookware is placed on the burner head. By using such a gas cooktop including the control system, the gas cooktop automatically adjusts the fire to a minimum after a user removes a cookware, thus reducing fume in a kitchen and reducing gas consumption.