The present invention provides a method for a simple and accurate measurement of triglycerides in low-density lipoprotein in a sample comprising performing the following steps sequentially:(i) a step of generating free glycerol by allowing lipoprotein lipase to act on a sample, in an aqueous medium comprising the sample and a specific surfactant such as polyoxyethylene polyoxyalkylene polycyclic phenyl ether; (ii) a step of removing free glycerol present in the reaction solution of the above step (i); (iii) a step of generating free glycerol by allowing lipoprotein lipase to act on the reaction solution from which free glycerol has been removed in step (ii), in the presence of a specific surfactant such as polyoxyethylene polyoxyalkylene alkyl ether; and (iv) a step of measuring free glycerol generated in step (iii), and a kit used for the method.