Tree green space has a remarkable positive effect on neighboring land and building prices mainly due to its shading and aesthetic quality. Yet, this value are often overlooked. This paper aims to estimate the effect of tree green space on building price in Jahanshahr neighborhood of Karaj city. Hedonic pricing method was used to value tree green space. The data on 220 residential real estate transactions in 2016 within study areas were obtained from the state-owned Rahbar informatics services company. Spatial information and characteristics of neighborhood and tree green space were collected using QuickBird satellite image and Arc Gis10/3 software. Tree green space neighboring studied buildings was quantified using the percentage of tree crown cover within different radius window surrounding the properties. Then, the optimal radius providing the highest correlation between tree cover and building prices was used in the hedonic model. The findings showed that the characteristics of building and tree green space have significant effects on per-m2 price of buildings. The optimal radius used to calculate tree cover around residential buildings found to be 300 meters. Price elasticity revealed that every 1% increase in the tree cover raise the per-m2 price by 0.6% at the sample mean. Therefore, tree green space in Jahanshar with average tree cover of 29/4 % raise the per-m2 price of buildings by 17/6 %. The results also showed that a 1% increase in the road distance to closest park reduces the per-m2 price of buildings by 9.1%. Finally, % morexpensive.