A padlock that can be unlocked by the owner of the padlock by dialing an unlocking number or by authorized security personals with a general key. The padlock mainly contains a lock body, a block, a shackle, a general locking device and a private locking device. The lock body has a first channel and a second channel therein. The block is engaged with the second channel. The block has a receptacle therein. The shackle has a longer arm slidably received in the first channel and a shorter arm engageable with the receptacle of the block. The general locking device is formed in the lock body for locking or unlocking the longer arm of the shackle. The private locking device is formed in the lock body for controlling movements of the block in order the block to be engaged with or disengaged from the shorter arm of the shackle.