Disclosed is a method for analyzing a sample solution, including introducing a sample solution 50 through a sample introduction part 6 and developing the sample solution 50 to a developing layer 2 through a capillary phenomenon to analyze an analyte contained in the sample solution 50, the sample introduction part 6 being provided on one side of a test strip 100 and the developing layer 2 being provided on the other side of the test strip 100, wherein the test strip 100 is disposed in such a development posture that the downstream region of the developing layer faces downward during the development. By this method, the developing rate is less susceptible to the viscosity of the sample solution 50 and thus has a small difference even among sample solutions 50 differing in viscosity. As a result, the analytical accuracy and reliability can be improved.