Chain type automatic screw feeding device and screw gun

The invention relates to a chain type automatic screw feeding device and a screw gun. The chain type automatic screw feeding device comprises: a shell, wherein the upper end of the shell is of an open structure, the open structure is provided with a rear opening and a front opening, the rear opening allows a screwdriver to enter the shell, and the front opening allows a screw in the shell to be pushed out by the screwdriver; chain wheels, wherein two chain wheels are provided, are arranged up and down at an interval, and are rotatably assembled in the shell; a chain in transmission connection with the two chain wheels, wherein a plurality of screw fixing clamps are arranged on chain links of the chain in the transmission direction of the chain, and the screw fixing clamps are used for clamping screws; and a push rod, wherein a pressing rotating mechanism is arranged between the push rod and the corresponding chain wheel, and direct motion of the push rod is converted into rotation of the chain wheels by press