Non-thermal atmospheric pressure plasma has been used to control cells’ activities in biomedical research field. Plasma can generate various active species which affects cells. However, since the active species diffuse before being supplied to cells cultured in the liquid medium, it was difficult to elucidate detailed mechanism of plasma effects on cells. This paper reports development of a simple plasma exposure system for cells. The system enables to directly supply gaseous plasma-generated active species to cells cultured in liquid medium by using a gas permeable thin film. The system developed here contributes to elucidate plasma effects on cells.