Abstract: A physiologically active substance controlled release composite composition is prepared by a process which comprises the steps of:adding a physiologically active substance to a physiologically active substance-containing adsorbent previously prepared by adsorbing the same or a different physiologically active substance onto an inorganic adsorbent, and dispersing and mixing;dispersing the resulting mixture in a polymerizable vinyl monomer containing 0 to 50% of synthetic high molecular weight subtance which is polymerizable at a temperature of below -20.degree. C.; and,after holding the desired shape, irradiating the resulting dispersion with an ionizing radiation at a temperature of -20.degree. to -100.degree. C. to polymerize.