Abstract: A gadget for retroreflected signal measurement is disclosed. The gadget for measuring the retroreflected signal includes a partitioning wall; a portable terminal receiving portion disposed on one surface of the partitioning wall; a biosensor receiving portion disposed on the other surface of the partitioning wall and constructed to receive a biosensor therein; a light exit channel defined in the partitioning wall and at one side thereof; and a light-receiving channel adjacent to the light exit channel and defined in the partitioning wall, wherein light passes through the light exit channel and then is reflected from the biosensor, and then is incident into the light-receiving channel.