A measurement was made in a street canyon with street trees (Abelia grandiflorarehd and Populus nigra.), which were planted along National Route 3 (Route 3), an asphalt- made road, in order to study inhibitive effects of street trees on surface temperature of urban area. The measurement was performed from June 1 to 2 in 1995, in Fukuoka, Japan. In this area Abelias are planted densely along both side of the road, trimmed in rectangular shape at the height of about 120 cm, while 7 m high Poplars are planted inside the bush of Abelias at intervals of 9 m. A thermal imagery thermometer was used to study characteristics of the distribution of surface temperatures in the street. The results obtained through the measurement and data analysis can be summarized as follows: 1) The shadow of tall and foliaged street trees projected on the surface of asphalt road had remarkable inhibitive effects on surface temperature. For example, the surface temperatures were 24℃ in the shadow of Poplar’s tree, and 40℃ outside of the shadow at 13 : 30. 2) In contrast to the marked temperature increasing on the road in urban area, street trees keep lower surface temperatures. In other word, the street trees perform cooling functions by transpiration and decreasing functions of heat island in urban area. 3) The effect of tall and heavy foliaged street trees were better than the short one in improving heat environment during daytime in urban area. 4) On the dried surface of asphalt road which is without functions of changing sensible heat into latent heat, the increasing rate of its surface temperature was twice of air temperature and 2.2-2.5 times of Poplar and Abelia. 5) The heat radiated from the part of asphalt road which had been under the shadow decreased to be about 80% of that from the sunny part of road during the daytime. From the stand point of road view, it is good for the road to plant some short trees like Abelia along it, but their meteorological effect can not be equal to the tall and foliaged trees. Of course, we should think over traffic safety and classes of road. If there is no special limitation on the type of tree, choosing tall and foliaged trees are recommended. On the other hand, the 9 m intervals of Poplar’s trees like Route 3 is too wide to cover the road surface with shadow. The method of arrangement of tall street trees is an important problem and should be researched from now on.