The present invention provides a safety device for elevators, which belongs to the field of elevator safety technologies. The safety device for elevators includes a housing; a safety piece having a guide rail groove, the safety piece being disposed in the housing; and asymmetric active and counter wedges that are slidably disposed on the safety piece at both sides of the guide rail groove, respectively. Moreover, the device further includes a U-shaped elastic element and a blocking piece that are disposed on the safety piece. The safety device for elevators can provide a relatively stable arresting force, is reliable in repetitive work, achieves high safety, is relatively easy as well as fast and efficient in restoration, and is especially suitable for high-speed elevators.