BIOSENSOR

It is an object of the present invention to provide an excellent biosensor which can perform supply of a sample solution accurately and easily. A biosensor which has a capillary (7) for collecting a sample solution and analyzes a specific substance in the sample solution is provided with, in addition to an air hole (9), at least two supply ports, i.e., a sample supply port (13) and an auxiliary sample supply port (14), so that supply of the sample solution can be performed from either of the supply ports (13) and (14). Even when the sample supply port (13) is closed up with a fingertip or the like and supply of the sample solution is stopped, the sample solution can be quickly supplied from the other auxiliary sample supply port (14).