PURPOSE: To provide a large water-holding capacity by forming at an underside of a drip pan a plurality of grooves having a substantially square-shaped cross-section and extending in a direction of inclination of the drip pan.

CONSTITUTION: Drip pans 20, 20' are provided above storage chambers 2, 2' to be inclined rearwardly and downwardly from openings 4, 4'. The drip pans 20, 20' are of the same construction, as the drip pan 20 described hereinbelow. The drip pan 20 comprises a drip pan plate 21 formed of ABS resin and channel-shaped members 25, 26 secured to both ends of the drip pan plate 21. Both edge portions of the drip pan plate 21 are bent upward to form guide portions 22, 22, and the drip pan plate is formed at an underside thereof with a plurality of substantially square-shaped grooves 23. The drip pan 20 is formed by fixing the both ends of the drip pan plate 21 in bottom portions of the channel-shaped members 25, 26 such that the grooves 23, 23 abut thereagainst at a right angle. Provided in the bottom portion of the channel-shaped member 26 are a plurality of drainage holes 28. Even when steam contained in air within the storage chambers produces condensation at the underside of the drip pan 20 in large quantities, condensed water is accommodated in the grooves 23 to flow therein to ends thereof in a direction of inclination. Water-holding capacity of the drip pans is so great that condensed water is permitted to be suitably discharged through the both end of the channel-shaped member 26 and the drainage holes 28 without dripping into the storage chambers from the both ends of the grooves 23.