PROBLEM TO BE SOLVED: To provide a biosensor measuring apparatus provided with a device for determining the start time of measurement. SOLUTION: An optical biosensor measuring apparatus includes a biosensor capable of being administered with a sample; a wavelength-variable light source 1502 for irradiating a variable-wavelength light source for detecting the reaction of the biosensor; an additional light source 1504 for irradiating a light source having a fixed wavelength for detecting the reaction initial time of the biosensor; a coupler 1505 for combining the light sources of the wavelength-variable light source 1502 and the additional light source 1504; a lens 1506 for forming parallel light out of the light sources combined through the coupler 1505; and an optical output measuring device 1508 for irradiating parallel light passed through the lens 1506 to the biosensor administered with the sample and detecting the reaction of the biosensor. COPYRIGHT: (C)2010,JPO&INPIT