A hot melt glue gun with an automatic glue stick feeding structure includes a gun-shaped housing, a press button, an automatic glue stick feeding device, a hot melt unit, a nozzle, and a control unit. The automatic glue stick feeding device includes a casing and a synchronous motor having a transmission shaft. The casing includes a transmission gear, an inlet, and at least one gear train having upper and lower gears and a passage. The control unit includes a control printed circuit board, a micro switch, a forward relay output control portion, and a rearward relay output control portion. A glue stick is moved forwards when a user slightly presses the press button. When the press button is not pressed, the glue stick moves rearwards, avoiding continuous dripping of the molten glue through a nozzle.