Photoirradiation effects on conductivity in the organic salt alpha-(BEDT-TTF)(2)I-3 at temperatures close to the metal-insulator (M-I) phase boundary are investigated using time-resolved measurements of photocurrent. The transient photocurrent at 115 K shows a remarkable persistence at the metallic conductivity and a nonlinear dependence on the light intensity, probably originating from the photoinduced M-I phase conversion in the presence of electric fields.