PROBLEM TO BE SOLVED: To provide a fruit color development promoting device in which the distance from a light source to a fruit can be easily adjusted and there are few restrictions on the size and number of fruits installed inside. SOLUTION: A fruit color development promoting device 1a is composed of a pair of light emitting units 4a and 4a including a light emitting portion 2a and a support portion 3, a guide unit 5 for holding the light emitting unit 4a, and a heat insulating material such as styrofoam. A bottom plate 6a is detachably attached so as to close the opening, and a rectangular parallelepiped housing 6 in which the light emitting units 4a and 4a and the guide unit 5 are housed is provided. [Selection diagram] Fig. 1【課題】光源から果実までの距離の調整が容易であるとともに、内部に設置される果実の大きさや個数に対する制約が少ない果実発色促進装置を提供する。【解決手段】果実発色促進装置1aは、発光部2aと支持部3からなる一対の発光ユニット4a,4aと、この発光ユニット4aを保持するガイドユニット5と、発泡スチロールなどの断熱材からなり、底面に開口部を塞ぐように底板6aが着脱可能に取り付けられるとともに、発光ユニット4a,4aとガイドユニット5が内部に収容される直方体状の筐体6を備えている。【選択図】図1