A riveting unit is assembled with an electric rivet gun, including a transmission unit, a clamping jaw having a locating portion driven by the transmission unit to be moveable between a first position and a second position, a first sensor detecting whether the locating portion of the clamping jaw is located at the first position, and a second sensor detecting whether the locating portion of the clamping jaw is located at the second position. When the locating portion of the clamping jaw is located at the first position, a blind rivet can be installed in the clamping jaw, and when the locating portion of the clamping jaw is located at the second position, the blind rivet can be ejected, and meanwhile the second sensor can allow the transmission unit to stop the movement of the clamping jaw, thereby preventing the clamping jaw from moving backwards excessively.