Abstract: A buckle includes a first fastener and a second fastener. The second fastener has two hooks. The first fastener includes a socket, a locking piece disposed in the socket, and two first locking portions formed on the socket for mating with the hooks. The locking piece is slidingly connected in the socket to cooperate with the second fastener. When the first fastener is engaged with the second fastener, the locking piece enters the second fastener to restrict the movement of the second fastener, so that the second fastener cannot be released unless the locking piece is removed from the second fastener and the hooks of the second fastener are pressed. Thus, the second fastener can be released only when the locking piece is moved, thereby preventing a problem that the second fastener may be separated from the first fastener when the hooks of the second fastener are incautiously pressed. A user has to move the locking piece with one hand and presses the hooks with another hand.