To freely increase or decrease the number of fluorescent lamps to be set on rear faces of shelf boards of an open showcase.

An input side of each of power supply receiving connectors 22 is connected to a commercially available power supply line 24, and each of fluorescent lamp connectors 32 is connected to the output side of each power supply receiving connector 22 through a pair of cords 30a, 30b. Each ballast stabilizer 34 is connected to an intermediate portion of the cord 30a, which is one of the cords, and the other cord 30b is directly connected to both the connectors. In this way, a plurality of units are provided which comprise power supply transion connectors 40-49 capable of connecting the output side of each of the respective power supply receiving connectors 22 to the input side of each of the respective power supply receiving connectors 22 of other units A.