To provide a piston which can realize further improvement in terms of suppression of thermal expansion/shrinkage and suppression of deformation caused by pressure fluctuation in a piston head.

The piston has the piston head of which the central part has an FRM (fiber-reinforced metal) comprising a matrix piston composed of A-390 and an alumina staple fiber dispersed in the matrix. In the central part of the piston head, a rich layer 8 is formed near the FRM side by causing the agglomeration of filtered primary silicon crystal 6 in a high concentration, and a poor layer 9 having a low concentration of the primary silicon crystal 6 is formed as the distance from the fiber cluster increases.