PROBLEM TO BE SOLVED: To provide a snowfall detection method, a snow melting control method, and a snow melting device which securely detect snowfall accumulated on the roof of horticulture facility, and furthermore enable the snowfall to be securely melt by a simple constitution.SOLUTION: A snow melting device 10 is provided that detects snowfall accumulated on a light-transmitting roof 2 of horticulture facility 1 having the roof 2, and performs snow melting processing based on the detection result. The snow melting device 10 comprises: an indoor light detector 13 provided in the horticulture facility 1； an outdoor light detector 14 provided outside the horticulture facility 1； and a control part C which calculates light transmittance into the horticulture facility 1 via the roof 2 based on a light quantity difference between outdoor light quantity detected by the outdoor light detector 14 and indoor light quantity detected by the indoor light detector 13, detects that there is snowfall on the roof 2 when the light transmittance is a predetermined value or less, and performs snow melting processing.SELECTED DRAWING: Figure 1【課題】簡易な構成で園芸施設の屋根に溜まった積雪を確実に検知し、さらにこの積雪を確実に融雪することができる積雪検知方法、融雪制御方法、及び融雪装置を提供する。【解決手段】光を透過する屋根２を有した園芸施設１の屋根２に溜まった積雪を検知し、この検知結果をもとに融雪処理を実行する融雪装置１０であって、園芸施設１内に設けられた屋内光検出器１３と、園芸施設１外に設けられた屋外光検出器１４と、屋外光検出器１４が検出した屋外光量と屋内光検出器１３が検出する屋内光量との差分光量をもとに屋根２を介した園芸施設１内への光透過率を算出し、光透過率が所定値以下の場合に屋根２に積雪があると検知し、融雪処理を実行させる制御部Ｃと、を備える。【選択図】図１
