A component for an artificial knee joint replacement, provided with: a femoral component having a femoral medial condyle, which has a semi-ellipsoid medial posterior condyle part which comes into contact with a tibial component during a bending and stretching movement, and a femoral lateral condyle, which has a semi-ellipsoid lateral posterior condyle part which comes into contact with the tibial component during a bending and stretching movement and the tibial component having a medial posterior condyle part contact surface, which comes into contact with at least the medial posterior condyle part, and a lateral posterior condyle part contact surface, which comes into contact with at least the lateral posterior condyle part. When, taking the spherical surface of the portion of the medial posterior condyle part at which the medial posterior condyle part and the medial posterior condyle part contact surface are in contact with each other at a bending angle of 0º to 90º to be a part of a true sphere, the spherical center of the true sphere is deemed to be a medial posterior condyle part spherical center, and taking the spherical surface of the portion of the lateral posterior condyle part at which the lateral posterior condyle part and the lateral posterior condyle part contact surface are in contact with each other at a bending angle of 0º to 90º to be a part of a true sphere, the spherical center of the true sphere is deemed to be a lateral posterior condyle part spherical center, the medial posterior condyle part has an outline shaped so that the diameter extending from the medial posterior condyle part spherical center to the lowermost point in the femoral component at which the medial posterior condyle part is in contact with the medial posterior condyle part contact surface decreases each time the bending angle increases from a given angle, and the lateral posterior condyle part has an outline shaped so that the diameter extending from the lateral posterior condy
