This invention provides a biological component-measuring device 1, enabling the operator to easily calibrate the entire device and capable of measuring biological components accurately, and a method for calibrating the device 1. The device measures a sample including a body fluid taken through a body fluid sampler 3a by sending it with a pump 10b through a sample channel 11a, 11d, 11e to a sensor 5. The device 1 includes a calibrating liquid channel 11h through which a calibrating liquid can be supplied to the sensor 5 via the sample channel 11a, 11d, 11e by a switching of a first flow path changeover valve 9b placed in the sample channel at a location upstream of the pump 10b and connected to the channel 11h. The method includes introducing the calibrating liquid from the channel 11h via the channel 11d, 11e into the sensor 5 by switching the valve 9b.
