A biological information detection apparatus includes a sensor having a light emitter that radiates light to a subject and a light receiver that receives light from the subject, and a contact part to be in contact with the subject. Supposing that light power from the light emitter passing through a living body and entering the light receiver is PS and a distance from the light receiver to an end portion of the contact part is rN, and light power of disturbance light from outside of the end portion passing through the living body and entering the light receiver is PN(rN) as a function of rN, an attenuation rate α of the disturbance light is set to satisfy rN≦10 mm and α≦PS/{PN(rN)×1000}.
