It is disclosed a method of forming fine patterns comprising repeating plural times the following course of steps: covering a substrate having thereon photoresist patterns with an over-coating agent for forming fine patterns, applying heat treatment to cause thermal shrinkage of the over-coating agent so that the spacing between the adjacent photoresist patterns is lessened by the resulting thermal shrinking action, and removing the over-coating agent. The invention provides a method of forming fine patterns which has high ability to control pattern dimensions and provide fine patterns that have a satisfactory profile and satisfy the characteristics required of semiconductor devices, even in the case of employing a substrate having thick-film photoresist patterns in a thickness of about 1.0 μm or more.