To precisely evaluate the impact of canopy heat storage on the energy balance of an apple orchard, heat storage flux and its diurnal changes were examined by observation during both growing and sprouting periods. The majority of canopy heat storage was trunk heat storage, followed by sensible and latent heat storages, while the leaf heat storage was negligible. The canopy heat storage flux peaked between 0700 and 0930 and bottomed out at around 1800. The range of diurnal flux was larger in the sprouting period than in the growing period, and likewise on days of higher solar radiation. It reached 66 Wm -2 on fine days in the sprouting period. By taking HS into account, the energy closure ratio for the eddy covariance method increased by 1.03 and 1.16 times in daytime and nighttime, respectively, and this increase was generally thought to improve the energy imbalance. The canopy heat storage flux could be well estimated from the difference of air temperature above the canopy at present and an hour before ).