The purpose of agroforestry systems is to establish forests by minimizing the friction between agricultural and silvicultural land-use. For harmonizing both and operating the system effectively, various studies must be undertaken not only from socio-economic but also from technical and scientific aspects. Multistoried system of agroforestry, where trees and agricultural crops form the upper and lower layers, respectively, can be observed very often in Southeast Asia. In this system, the upper layer controls the light climate for the lower crops. Light is an essential factor for the growth of plants. Therefore, analyses of the light climate under the forest canopy were attempted in this report. Light measurement under the shade showed the importance of differentiation between direct and diffuse fractions of sunlight. Only the diffuse fraction affected the light climate under the shade. There was a high positive correlation between the diffuse light measured under the canopy and the opening proportion in the canopy visualized by hemispherical photographs. Based on actual measurements of sunlight in the forest and hemispherical photography, the light reaching the ground was evaluated in connection with the stand structure. Furthermore, the relationship between the light conditions under the canopy and the stand structure was illustrated diagrammatically, and the possibility of light management was suggested.