The present invention addresses the problem of providing an exceptional GLP-1 secretagogue that is a component derived from milk, a composition for promoting GLP-1 secretion, and a food/beverage or drug containing the same. Any selected from the group consisting of micellar casein, a hydrolysate thereof, a fraction thereof, a purified product thereof, and peptides including an amino acid sequence indicated by any of SEQ ID NOS.: 1-7 is configured as an active ingredient of a GLP-1 secretagogue and a composition for promoting GLP-1 secretion.
