Reinforcing member, production method therefor, and engine block

A portion of a reinforcing member has a stacked structure in which plural iron plates having openings are stacked. A hollow portion is formed inside the stacked structure , so that the reinforcing member is reduced in weight. Porous bodies composed of non-woven fabric of metal fibers are disposed on surfaces contacting matrixes, so that adhesion between the reinforcing member and the matrix is improved, and peeling therebetween is prevented. A cast product which is composed of light metal and has the above reinforcing member has a small thermal expansion. For example, the cast product is desirable for use for a journal portion of an engine block.