An object is to perform analysis of a target component contained in a small volume of blood sample at high accuracy using a normal component homeostatically present in blood. Provided is a blood test kit for analyzing a concentration of a target component in a blood sample by using a normal component homeostatically present in blood, the kit including: a diluent solution for diluting a blood sample； and a member selected from the group consisting of a first storing instrument in which the diluent solution is stored, a separating instrument for separating and recovering blood plasma from the blood sample diluted with the diluent solution, a holding instrument for holding the separating instrument, a second storing instrument for storing the recovered blood plasma, and a sealing instrument for keeping the stored blood plasma in the second storing instrument, in which an amount of the normal component which is derived from the member and may be contained in the diluent solution is defined.
