The information detector (100) includes an irradiating means (110) for irradiating light, a reflecting means (425) having a different reflectance from the object to be measured (500), and a light receiving means for receiving return light of the light irradiated from the light emitting part And a discriminating means (160) for discriminating whether or not the return light is return light from the measurement target or return light from the reflection means based on the amount of light received by the light receiving means . Thus, for example, it can be determined whether or not a device is normally attached to the measurement target, and measurement of suitable biological information can be realized.情報検出器(100)は、光を照射する照射手段(110)と、計測対象(500)とは異なる反射率を有する反射手段(425)と、発光部から照射された光の戻り光を受光する受光手段(120)と、受光手段における受光量に基づき、戻り光が、計測対象からの戻り光であるのか、又は反射手段からの戻り光であるのかを判別する判別手段(160)とを備える。これにより、例えば計測対象に対して正常に装置が取付けられているか否かを判別でき、好適な生体情報の計測を実現できる。
