Satisfactory effects have not always been attained by immunotherapy having been tried, and reliance upon direct attack on cells by anticancer agents, radiation, etc has been inevitable. The present invention intends to provide a therapeutic method that ensures less side effects but higher efficacy than in conventional therapeutic methods through enhancing of immune strength inherently had by living organism. Thus, the present invention relates to an immunopotentiating agent comprising MIP-1.alpha. or its functional derivative as an active ingredient.