A safety device for an elevator, comprising: a housing that is supported by a car guided along a guide rail, and displaceable horizontally with respect to the guide rail; a receiving brake member disposed in the housing; and a rotatable brake member that is arranged at a distance from the receiving brake member so that the guide rail is interposed between the rotatable brake member and the receiving brake member, the rotatable brake member being vertically rotatable about a rotating shaft disposed in the housing, and grasping the guide rail in cooperation with the receiving brake member by the vertical rotation about the rotating shaft; wherein the rotatable brake member comprises a rolling contact portion whose distance from the receiving brake member is continuously smaller even when the rotatable brake member rotates, wherein the rolling contact portion is configured along an outer peripheral surface of one cylinder having an axial line eccentric to a center line of the rotating shaft and wherein the safety device for an elevator further comprises a displacement drive mechanism that displaces the housing with respect to the car in a direction along which the rotatable brake member comes in or out of contact with the guide rail, characterized in that the distance of the rolling contact portion from the receiving brake member is continuously smaller even when the rotatable member rotates in any one of upper and lower direction, and in that the displacement drive mechanism includes: a plurality of urging springs that urge the housing in a direction along which the rotatable brake member comes in contact with the car guide rails, and a hold/release mechanism that is capable of regulating a displacement of the housing against an urging force of the urging springs. a housing that is supported by a car guided along a guide rail, and displaceable horizontally with respect to the guide rail; a receiving brake member disposed in the housing; and a rotatable brake member that is arranged at a distance from the receiving brake member so that the guide rail is interposed between the rotatable brake member and the receiving brake member, the rotatable brake member being vertically rotatable about a rotating shaft disposed in the housing, and grasping the guide rail in cooperation with the receiving brake member by the vertical rotation about the rotating shaft; wherein the rotatable brake member comprises a rolling contact portion whose distance from the receiving brake member is continuously smaller even when the rotatable brake member rotates, wherein the rolling contact portion is configured along an outer peripheral surface of one cylinder having an axial line eccentric to a center line of the rotating shaft and wherein the safety device for an elevator further comprises a displacement drive mechanism that displaces the housing with respect to the car in a direction along which the rotatable brake member comes in or out of contact with the guide rail, characterized in that the distance of the rolling contact portion from the receiving brake member is continuously smaller even when the rotatable member rotates in any one of upper and lower direction, and in that the displacement drive mechanism includes: a plurality of urging springs that urge the housing in a direction along which the rotatable brake member comes in contact with the car guide rails, and a hold/release mechanism that is capable of regulating a displacement of the housing against an urging force of the urging springs. a plurality of urging springs that urge the housing in a direction along which the rotatable brake member comes in contact with the car guide rails, and a hold/release mechanism that is capable of regulating a displacement of the housing against an urging force of the urging springs.