A thin film forming composition for forming resist underlayer film useable in the production of a semiconductor device, and a resist upper layer film absorbs undesirable UV light with a thin film as an upper layer of the EUV resist before undesirable UV light reaches the EUV resist layer in EUV lithography, an underlayer film (hardmask) for an EUV resist, a reverse material, and an underlayer film for a resist for solvent development. The thin film forming composition useable together with a resist in a lithography process, comprising a mixture of titanium compound (A) selected from: R0aTi(R1)(4-a)  Formula (1) a titanium chelate compound, and a hydrolyzable titanium dimer, and a silicon compound (B): R2a′R3bSi(R4)4-(a′+b)  Formula (2) a hydrolysis product, or a hydrolysis-condensation product of the mixture, wherein the number of moles of Ti atom is 50% to 90% relative to the total moles in terms of Ti atom and Si atoms in the composition.