A folding device for a golf cart includes a main part to which two side wheels, a handle and a front wheel unit are connected. A tubular portion is movably mounted to a front wheel stem and a connection member is connected between the tubular member and a handle stem. Two rods are connected between side wheel stems. An operation member is pivotably connected to the tubular portion and has notches so that the protrusion of the main part is engaged with the notches to control the main part to connect to or to separate from the tubular member. The tubular member is movable on the front wheel stem so as to fold or expand the front wheel unit.