A torsional vibration damper is provided that is capable of increasing torsional rigidity without increasing a size of an elastic member in a radial direction. A torsional vibration damper includes a boss member and a disk plate provided coaxially with each other; an elastic member being elastically deformable in a rotation direction of the boss member; a cam member rotating integrally with the boss member; a torque transmission member transmitting rotation torque between the boss member and the disk plate; and a socket member provided between the torque transmission member and the elastic member and having a contact surface coming in contact with the torque transmission member. The torque transmission member is capable of entirely reciprocating in a radial direction of the boss member in accordance with rotation of the cam member, and elastically compresses the elastic member when it moves outward in the radial direction of the boss member.