A method of forming a pattern with dots or holes arranged in a two-dimensional period by illuminating, with illumination light, a mask having a light-shielding portion pattern on a translucent substrate, and performing projection and exposure of an object to be exposed through a projection optical system. The illumination light is an effective light source of multipole illumination. A first exposure process is performed with the mask placed at a first position relative to the object to be exposed, and a second exposure process is performed with the mask placed at a second position. The mask has line patterns having lines with a line width a [m] arranged in parallel at a pitch of P. The line patterns are arranged in a mesh such that the line patterns intersect one another at 60° in three directions, and the illumination light is an effective light source of hexapole illumination. The second exposure process is performed, after the first exposure process, with the mask placed at a second position displaced from the first position by 2P/3 [m] in a direction perpendicular to any line of the line patterns. A third exposure process is performed, after the second exposure process, with the mask placed at a third position further displaced from the second position by 2P/3 [m] in the direction, to thereby form a dot pattern in a two-dimensional period having a pitch of P/3 [m].