The lifetime evaluation study for a fusion reactor first wall was performed using newly developed one-dimensional analysis code. Since the in-vessel components are exposed to a severe and complex environment, the evaluation of their lifetime is required for the design of fusion reactors. In the present paper, the first wall was assumed to be a flat plate and free to expand but not bend. Linear fracture mechanies was used to investigate the crack growth behavior and parametric surveillance was performed changing the swelling rate, initial crack length and wall loading. It is concluded that 1) the crack growth from the plasma side will limit the lifetime of the first wall, and 2) fracture toughness and initial crack length are the most important limiting factors for the first wall lifetime.