In an artificial knee joint implant, an increase in constraint force of a femur component and a tibia component in the anterior-posterior direction and the left-right direction of a patient is enabled, and an increase in an allowable degree of medial pivot motion is enabled. An artificial knee joint implant has a femur component to be fixed to a distal portion of a femur of a patient, and a tibia component to be fixed to a proximal portion of a tibia of the patient. Femur sliding faces of the femur component and tibia sliding faces of the tibia component each include a region in which the curvature radius varies in a predetermined direction.