Abstract: The present invention relates to a reagent for selective measurement of triglycerides contained in very low density lipoprotein and intermediate density lipoprotein or in very low density lipoprotein in a test sample, including a first reagent that contains a first selective reaction promoter, which is an ether or ester compound of a polyoxyalkylene capable of reacting lipoprotein lipase selectively with triglycerides contained in low density lipoprotein and high density lipoprotein; lipoprotein lipase; enzymes which catalyze a series of reactions leading to the generation of hydrogen peroxide or a reduced coenzyme from glycerol; and an enzyme which catalyzes a reaction leading to the conversion of hydrogen peroxide or a reduced coenzyme into another substance, and a second reagent that contains a second selective reaction promoter, which is capable of reacting lipoprotein lipase selectively with triglycerides contained in very low density lipoprotein, intermediate density lipoprotein, low density lipoprotein