A padlock having an open indication function is provided. The padlock includes a first lock, a driving device, and an indication device. A portion of the driving device is movably disposed within a key hole of the first lock. The indication device moves in combination with the driving device. A bottom end of the indication device is connected to a top end of the driving device. In addition, the indication device is selectively disposed between a first position and a second position. When a key is inserted into the key hole of the first lock, the key pushes the driving device to force the indication device moving from the first position to the second position.