An attempt was made to develop a simple testing method fro blast resistance in the aged rice plant grown under the paddy field conditions. The blast resistance was tested with the detached 3rd leaves from the top of the plant, which were inoculated by dropping blast spore suspension mixed with 1% Tween 20 on the punched area and kept in 1% sucrose solution. The blast reaction was measured ten days after incubation at 26-28$^{circ}C$ under highly humid conditions. With this method blast resistant lines were effectively identified and the cost of testing was cheap as compared with any other methods ever practiced.