A shock absorber comprising: a cylinder in which oil is sealed; a piston slidably fitted into the cylinder; a piston rod connected to the piston and extending to an outside of the cylinder; and a damping force generating apparatus controlling a flow of the oil generated by a sliding movement of the piston inside the cylinder, wherein the damping force generating apparatus comprises a valve body generating damping force by being opened and closed on a flow path in which the oil flows, a valve seat closing the flow path when the valve body is seated, and an actuator generating thrust to the valve body in a valve closing direction, and the valve seat comprises a first elastic body which is elastically deformable in the valve closing direction of the valve body, wherein the valve seat comprises a valve seat portion on which the valve body is seated, wherein the flow path comprises a first flow path provided in an upstream side in an oil flow direction with respect to the valve seat portion, a second flow path provided in a downstream side in the oil flow direction with respect to the valve seat portion, and a valve body back pressure chamber communicated to the second flow path and allowing an oil pressure to act on the valve body in the valve closing direction, a first pressure receiving portion which is at least a part of the valve body receives a pressure in a valve opening direction by an oil pressure of the first flow path, a second pressure receiving portion which is at least a part of the valve body and which is different from the first pressure receiving portion receives a pressure in the valve closing direction by the oil pressure of the valve body back pressure chamber communicated to the second flow path, characterized in that a pressure receiving area of the first pressure receiving portion is equal to a pressure receiving area of the second pressure receiving portion. a cylinder in which oil is sealed; a piston slidably fitted into the cylinder; a piston rod connected to the piston and extending to an outside of the cylinder; and a damping force generating apparatus controlling a flow of the oil generated by a sliding movement of the piston inside the cylinder, wherein the damping force generating apparatus comprises a valve body generating damping force by being opened and closed on a flow path in which the oil flows, a valve seat closing the flow path when the valve body is seated, and an actuator generating thrust to the valve body in a valve closing direction, and a valve body generating damping force by being opened and closed on a flow path in which the oil flows, a valve seat closing the flow path when the valve body is seated, and an actuator generating thrust to the valve body in a valve closing direction, and the valve seat comprises a first elastic body which is elastically deformable in the valve closing direction of the valve body, wherein the valve seat comprises a valve seat portion on which the valve body is seated, wherein the flow path comprises a first flow path provided in an upstream side in an oil flow direction with respect to the valve seat portion, a second flow path provided in a downstream side in the oil flow direction with respect to the valve seat portion, and a valve body back pressure chamber communicated to the second flow path and allowing an oil pressure to act on the valve body in the valve closing direction, a first flow path provided in an upstream side in an oil flow direction with respect to the valve seat portion, a second flow path provided in a downstream side in the oil flow direction with respect to the valve seat portion, and a valve body back pressure chamber communicated to the second flow path and allowing an oil pressure to act on the valve body in the valve closing direction, a first pressure receiving portion which is at least a part of the valve body receives a pressure in a valve opening direction by an oil pressure of the first flow path, a second pressure receiving portion which is at least a part of the valve body and which is different from the first pressure receiving portion receives a pressure in the valve closing direction by the oil pressure of the valve body back pressure chamber communicated to the second flow path, characterized in that a pressure receiving area of the first pressure receiving portion is equal to a pressure receiving area of the second pressure receiving portion.