Abstract: A wearable device to accurately detect biometric information of the user. The wearable device includes a ring body; a light emitting element which is disposed in the ring body, and is configured to emit light toward a center side of a ring; and a first optical element which is disposed in the ring body to be closer to the center side of the ring than the light emitting element, and is configured to change a direction of travel of the light to a direction narrowing a directional angle of the light. The ring body includes a protrusion on an inner peripheral surface of the ring body where the first optical element is disposed, and the protrusion is formed to protrude closer to the center side of the ring than another part of the inner peripheral surface where the first optical element is not disposed.