A connection device includes: a pedestal having a placement face; a connector provided in the placement face of the pedestal; a support provided adjacent to the pedestal and extended in a direction crossing the placement surface of the pedestal and having a face to define a space for placing a portable terminal on the connector and on a contact face in the face of the support, the contact face being movable in a thickness direction of the support; and an elastic member that is deformed by the movement of the contact face and applies an elastic force generated by the deformation in a direction of blocking the movement of the contact face with respect to the thickness direction of the support.