To obtain a structure which can compensate an energy shortage by utilizing solar energy as electric energy for activities and further fixing the solar energy as thermal energy, without avoiding the solar energy, in the place and time of the adequate presence of sunlight.

A roof member 2 and/or a wall member 3 for forming an internal space are/is formed of a water layer 5 in which water is passed between translucent members which are doubly arranged; a light-condensing layer 6, which is composed of solar cells 6a with a remaining gap capable of securing daylighting required for the internal space, is formed in the inner or outer surface of the water layer 5; and a surface for covering the internal surface serves as a daylighting device with heat insulating properties.