To reduce a load of wiring work at an installation site.

A cooler chamber 30 made of foaming resin is mounted on a unit base 20, and it is installed so as to cover an opening 14 of a top face 10A of a refrigerator body 10. A housing chamber 50 of an internal lamp 100 is indented in area facing the opening 14 in an outer bottom face of the cooler chamber 30. A drain pan 60 made of synthetic resin receiving defrost water is provided in a lower face side of a cooler 32 in the cooler chamber 30, a pair of attachment parts 67 formed with a lower hole 68 is integrally formed on the lower face, and the attachment part 67 is passed through an insertion hole 51 formed on a bottom wall 40A of the cooler chamber 30 to face a ceiling face of the housing chamber 50. The internal lamp 100 is attached to the ceiling face of the housing chamber 50 by fixing a lamp base 103 to the attachment part by a tapping screw 106. A lead wire 109 of the internal lamp 100 is connected beforehand to an electrical component box 35 provided in the cooling unit 30.