As investigation of the relation between adhesion on rake face of tool and machined surface for some commercial aluminum alloys, the following result was obtained. The adhesion appeared on the rake face has two types, in the former type, adhered material on the rake face was thin and the evaluation of adhesion area varied. In the latter type, adhered material on the rake face was thick and the evaluation of adhesion area was stable. In the case of thin adhesion, the surface roughness after machining Ra has small value and increase with increasing adhesion area A. On the other hand, in the case of thick adhesion, Ra has large value and decrease with increasing A.