PURPOSE: To reduce the distortion of a pattern after exposure to light, make resolution uniform, and improve the shape fidelity of pattern edge part, by making the translation motion of a mirror synchronously with the swing of the mirror.

CONSTITUTION: The title method is applied to the constitution wherein the irradiation region for a plate type object group 3 to be exposed to synchrotron radiation light outputted from a light source O is enlarged by swinging a light refleting mirror 1 in a pivotary motion manner. The translation motion is made synchronously with the swing of a mirror 1, thereby obtain the state where the conjugate light source O' of the mirror is always still viewing from each point of the group 3. When the mirror 1 is swing by an angle θ, the light source O' is moved by l×2θ in the opposite direction. Hence, when the mirror 1 is moved parralel to the direction to cancel the above amount synchronously with the swing, the light source O' is positioned at the same point.