The present invention relates to a magnetoresistive effect element, magnetic head, magnetic storage device and magnetic memory device. A magnetoresistive effect element of a CPP type includes a fixed magnetization layer, a non-magnetic layer and a free magnetization layer formed of CoFeAl. The CoFeAl has a composition falling within a range defined by straight lines connecting points A, B, C, D, E, F and A, in that order, in a ternary composition diagram. The point A is (55, 10, 35), the point B is (50, 15, 35), the point C is (50, 20, 30), the point D is (55, 25, 20), the point E is (60, 25, 15), and the point F is (70, 15, 15), where coordinates of the composition of each point is represented by (Co content, Fe content, Al content). Each content is expressed by atomic percent.