The present invention relates to a lighting apparatus and a lighting apparatus assembly using the same. The lighting apparatus includes a light-emission unit having a plate shape; and a base unit configured to be detachably attached thereto the light-emission unit. The base unit has a substantially rectangular shape. The base unit includes a power supply rail for supplying electricity to the light-emission unit and a support section supporting the light-emission unit. The power supply rail has a rail-shape and extends in a longitudinal direction of the base unit. The light-emission unit includes a luminescent panel, a control circuit configured to control lighting of the luminescent panel and an electrically conductive connection terminal electrically connecting the control circuit to the power supply rail. The base unit is formed so as to be capable of being attached thereto a plurality of the light-emission units along the longitudinal direction of the base unit. The connection terminal is connected to an arbitrary point of the rail-shaped power supply rail.