An object of the present invention is to provide a blood analysis method and a blood test kit, which are for performing quantitative analysis of components by precisely obtaining a dilution factor. According to the present invention, provided is a blood analysis method including: a step of diluting a collected blood sample with a diluent solution； a step of determining a dilution factor by using a normal value of a normal component which is homeostatically present in blood； and a step of analyzing a concentration of a target component in the blood sample, in which the blood analysis method uses a member selected from the group consisting of a first storing instrument for storing the diluent solution, a collection instrument for collecting the blood, a separation instrument for separating and recovering blood plasma from the blood sample diluted with the diluent solution, a holding instrument for holding the separation instrument, and a second storing instrument for storing the recovered blood plasma, and in which the dilution factor is corrected after calculating in advance an amount of the normal component derived from the diluent solution, and/or an amount of the normal component derived from at least one of the members which may be contained in the diluent solution.
