As a substantial example, when the electrode active material is a carbon-based negative electrode active material, a raw material including core-shell composite particles of carbon-based negative electrode active material core-carbon precursor shell is press-molded to produce a molded body, and then heat-treated to convert the carbon precursor of the shell into carbon to produce the active material bulk. In contrast, a raw material including carbon-based negative electrode active material core particles and a carbon precursor (melt phase, solid or dissolved phase dissolved in a solvent) is mixed and press-molded to produce a molded body, which is then subjected to heat treatment to convert the carbon precursor in the state of being coated on core particles into carbon to produce the active material bulk.