A radiation sensitive composition including a siloxane polymer exhibiting phenoplast crosslinking reactivity as a base resin, which is excellent in resolution and can be used as a radiation sensitive composition capable of allowing a pattern having a desired-shape to be formed with sufficient precision. A radiation sensitive composition including as a silane, a hydrolyzable silane, a hydrolysis product thereof, or a hydrolysis-condensation product thereof; and a photoacid generator, in which the hydrolyzable silane includes hydrolyzable silanes of Formula (1) R1aR2bSi(R3)4-(a+b)  Formula (1) wherein R1 is an organic group of Formula (1-2) and is bonded to a silicon atom through a Si—C bond or a Si—O bond, and R3 is a hydrolyzable group; and Formula (2) R7cR8dSi(R9)4-(c+d)  Formula (2) wherein R7 is an organic group of Formula (2-1) and is bonded to a silicon atom through a Si—C bond or a Si—O bond, and R9 is a hydrolyzable group.