1. A method for causing photosynthesis via a photosynthetic device comprising the steps:injecting chloroplasts and normal saline solution into a micro channel;
ceaselessly injecting chloroplasts and normal saline solution into said micro channel; and
radiating said micro channel simultaneously in order to cause photosynthesis within said micro channel;
wherein, the photosynthetic device includes a main body defining a microfluid chamber for causing photosynthesis therein, said microfluid chamber is constituted by a communication room, a plurality of said micro channels respectively and spatially communicated with said communication room, at least one micro injection duct spatially communicated with said communication room, and a plurality of filter plugs spatially connected to said micro channels respectively and said micro injection duct at free ends thereof in order to filter fluid backflow in said micro channels and said micro injection duct.