An object of the present invention is to provide an emulsion coagulant having excellent coagulation performance and a tire puncture repair kit that uses the emulsion coagulant. The emulsion coagulant of the present invention is an emulsion coagulant containing an α-starch and an anionic polyacrylamide; a molecular weight of the anionic polyacrylamide being from 500,000 to 2,000,000; and a mass ratio (WA:WB) of a content (WA) of the α-starch to a content (WB) of the anionic polyacrylamide being from 5:95 to 80:20.