An artificial knee joint includes a femoral component and a tibial plate. The femoral component includes a first joint face disposed adjacent to a medial collateral ligament of a patient, and a second joint face disposed adjacent to a lateral collateral ligament of the patient. The first and second joint faces respectively have first and second medial pivot guide portions. A reference face extending orthogonal to the left-right direction is defined between the first and second joint faces. An amount ΔD2 of decrease in a distance D2 between the second contact portion on the second medial pivot guide portion and the reference face in accordance with an increase per unit flexion angle is greater than an amount ΔD1 of decrease in a distance D1 between the first contact portion on the first medial pivot guide portion and the reference face in accordance with the increase per unit flexion angle.
