To provide a safety hook that can securely prevent detachment even against unprepared external force without spoiling easy attachment/detachment characteristics, and is high in versatility.

A safety hook 1 comprises an uncate hook part 2 and a closing body 4 which is sectioned substantially in a channel shape. The closing body 4 has a support shaft-side end part 4a pivoted in a swingable state on a base part 2a of the hook part 2 by a support shaft 8. Further, the closing body 4 is energized by a coil spring 10 outward in a rotating direction, and a free end 4b stays stable abutting against a tip part 2c of the hook part 2 from inside. Curved long holes 5 are formed in opposite side plates 4c of the closing body 4 respectively. A long hole 5 is curved on the side of the free end 4b to project inward in the rotating direction, and has a bent part 5a formed outward in the rotating direction on the side of the support shaft-side end part 4a. A slide pin 6 is arranged slidably in the long hole 5.