PROBLEM TO BE SOLVED: To provide a biological information detector and the like which can give proper initial pressure to a subject while reducing negative effects by pressure fluctuation or the like.SOLUTION: A biological information detector includes: a detecting part which has a light receiving part 140 for receiving light from a subject a translucent member 30 which is provided at a case surface side that comes in contact with the subject of the biological information detector, transmits light from the subject, and has a projection part 40 that comes in contact with the subject and presses it when measuring biological information of the subject and a pressure suppressing part 60 which is provided so as to encircle the projection part 40 on the case surface, and suppresses the pressure the projection part 40 gives to the subject. When a value obtained by subtracting a height HB of the pressure suppressing part 60 from a height HA of the projection part 40 in the direction orthogonal to the case surface is &Dgrh, &Dgrh>0 is satisfied.
