Provided is a sensor of a design in which a bodily surface is illuminated with light by light-emitting elements, and light passing through the body and reaching photoreceptor elements is received thereby, and is detected as a pulse wave signal indicating change in the diameter of arterial blood vessels within the body. The sensor has a light-emitting element array in which a plurality of the light-emitting elements are arrayed in a first direction, and a photoreceptor element array in which a plurality of the photoreceptor elements are arrayed in the first direction. The light-emitting element array and the photoreceptor element array are arranged such that, when viewed in a second direction orthogonal to the first direction, the area in which the light-emitting elements in the light-emitting element array are formed, and the area in which the photoreceptor elements are formed in the photoreceptor element array, are not lined up.
