We developed a spatially focused reagent injection system using 3-D sheath flow scanner. The proposed 3-D sheath flow scanner enables to introduce reagent specifically to target cell colonies cultivated in a microchamber. SiO 2 mesh strainer is formed in the microwell to improve spatial resolution of the reagent flow. This enables selective delivery of the reagent to target cell colonies cultivated in the microwell. The specific reagent flow is shifted by eight buffer flows which are controlled by four electro-osmotic flow (EOF) pumps. High performance positioning is realized by PC control with a joystick. Observation of confocal fluorescent image confirmed that the reagent flow is focused to small spot of about 100μmf on the mesh strainer where biological cells are cultivated.