Provided is an artificial knee joint implant that allows a more natural medial pivot motion to be performed. An artificial knee joint implant 1 includes a femoral component 2 and a tibial plate 4 that are in contact with each other. The femoral component 2 includes a first joint face 11 that is to be disposed adjacent to a medial collateral ligament 105 of a patient, and a second joint face 12 that is to be disposed adjacent to a lateral collateral ligament 106 of the patient. The first joint face 11 and the second joint face 12 respectively have a first medial pivot guide portion 46 and a second medial pivot guide portion 48. A reference face 43 extending orthogonal to the left-right direction is defined between the first joint face 11 and the second joint face 12. An amount ΔD2 of decrease in a distance D2 between the second contact portion 42 on the second medial pivot guide portion 48 and the reference face 43 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 41 on the first medial pivot guide portion 46 and the reference face 43 in accordance with the increase per unit flexion angle.
