A lighting system comprising: a mounting member attachable to a mounting surface; and a planar light source detachably attached to the mounting member, the planar light source being supplied with power from the mounting member to emit planar light, wherein the planar light source comprises: an engaging part engageable with a portion of the mounting member; a planar-light-emitting panel having a light-emitting surface that emits the planar light; and a connecting unit disposed between the engaging part and the planar-light-emitting panel, the engaging part constituting a portion of a power supply path for supplying power from the mounting member to the planar-light-emitting panel, the planar-light-emitting panel including a planar-light-emitting tile and a translucent plate that protects the planar-light-emitting tile, one main surface of the planar-light-emitting tile including a light-emitting region, wherein the planar-light-emitting panel, in a lighting state, emits the planar light from the light-emitting region of the planar-light-emitting tile through the translucent plate, wherein an output of the planar light from the planar light source is adjusted by pushing the light-emitting surface, wherein the mounting member comprises a duct rail extending in a predetermined direction, wherein the planar light source, in a state attached to the mounting member, is movable in an extending direction of the duct rail, wherein the connecting unit includes a push switch member, the push switch member including a pair of switch mechanisms, the pair of switch mechanisms being disposed to oppose to each other, the pair of switch mechanisms being disposed in a direction perpendicular to the light-emitting surface, and wherein the pair of switch mechanisms are electrically connected in the lighting state and are electrically disconnected in a non-lighting state. a mounting member attachable to a mounting surface; and a planar light source detachably attached to the mounting member, the planar light source being supplied with power from the mounting member to emit planar light, wherein the planar light source comprises: an engaging part engageable with a portion of the mounting member; a planar-light-emitting panel having a light-emitting surface that emits the planar light; and a connecting unit disposed between the engaging part and the planar-light-emitting panel, the engaging part constituting a portion of a power supply path for supplying power from the mounting member to the planar-light-emitting panel, the planar-light-emitting panel including a planar-light-emitting tile and a translucent plate that protects the planar-light-emitting tile, one main surface of the planar-light-emitting tile including a light-emitting region, wherein the planar-light-emitting panel, in a lighting state, emits the planar light from the light-emitting region of the planar-light-emitting tile through the translucent plate, wherein an output of the planar light from the planar light source is adjusted by pushing the light-emitting surface, wherein the mounting member comprises a duct rail extending in a predetermined direction, wherein the planar light source, in a state attached to the mounting member, is movable in an extending direction of the duct rail, wherein the connecting unit includes a push switch member, the push switch member including a pair of switch mechanisms, the pair of switch mechanisms being disposed to oppose to each other, the pair of switch mechanisms being disposed in a direction perpendicular to the light-emitting surface, and wherein the pair of switch mechanisms are electrically connected in the lighting state and are electrically disconnected in a non-lighting state. an engaging part engageable with a portion of the mounting member; a planar-light-emitting panel having a light-emitting surface that emits the planar light; and a connecting unit disposed between the engaging part and the planar-light-emitting panel, the engaging part constituting a portion of a power supply path for supplying power from the mounting member to the planar-light-emitting panel, the planar-light-emitting panel including a planar-light-emitting tile and a translucent plate that protects the planar-light-emitting tile, one main surface of the planar-light-emitting tile including a light-emitting region, wherein the planar-light-emitting panel, in a lighting state, emits the planar light from the light-emitting region of the planar-light-emitting tile through the translucent plate, wherein an output of the planar light from the planar light source is adjusted by pushing the light-emitting surface, wherein the mounting member comprises a duct rail extending in a predetermined direction, wherein the planar light source, in a state attached to the mounting member, is movable in an extending direction of the duct rail, wherein the connecting unit includes a push switch member, the push switch member including a pair of switch mechanisms, the pair of switch mechanisms being disposed to oppose to each other, the pair of switch mechanisms being disposed in a direction perpendicular to the light-emitting surface, and wherein the pair of switch mechanisms are electrically connected in the lighting state and are electrically disconnected in a non-lighting state.