A device includes a body part and a wearable part integrally attached to the body part and to be worn on a finger, and includes a light source unit and a light receiving unit that are arranged so as to oppose each other. The body part includes an electric circuit including a signal processor, a power supply unit, and a first terminal unit electrically connected to the electric circuit, and the wearable part includes at least one of the light source unit and the light receiving unit, and a second terminal unit electrically connected to the at least one of them. The first and second terminal units are mechanically in contact with and electrically connected to each other. The signal processor acquires a digital value concerning a pulse wave based on a signal output from the light receiving unit receiving light from the light source unit via the finger.