A composition for forming a silicon-containing resist underlayer film comprising: a silicon-containing compound obtained by a hydrolysis-condensation reaction of a mixture containing, at least, one or more hydrolysable silicon compound shown by the following general formula and one or more hydrolysable compound shown by the following general formula, R 1 m1 R 2 m2 R 3 m3 Si (4-m1-m2-m3) wherein, R represents a hydrocarbon group having 1 to 6 carbon atoms; at least one of R 1, R 2, and R 3 is an organic group selected from the groups shown by the following structural formulae, while the other is a hydrogen atom or a monovalent organic group having 1 to 30 carbon atoms; and m1, m2, and m3 represent 0 or 1 and satisfy 1≤m1+m2+m3≤3; U(OR 4) m4 (OR 5) m5 wherein, R 4 and R 5 represent an organic group having 1 to 30 carbon atoms, and m4+m5 is the same number as the number determined by valency of U; m4 and m5 represent an integer of 0 or more; and the U is an element belonging to groups of III, IV, or V in a periodic table except for carbon and silicon; a silicon-containing compound obtained by a hydrolysis-condensation reaction of a mixture containing, at least, one or more hydrolysable silicon compound shown by the following general formula and one or more hydrolysable silicon compound shown by the following general formula, R 6 m6 R 7 m7 R 8 m8 Si(OR 9) (4-m6-m7-m8) wherein, R 9 represents an alkyl group having 1 to 6 carbon atoms, and each R 6, R 7, and R 8 represents a hydrogen atom or a monovalent organic group having 1 to 30 carbon atoms; and m6, m7, and m8 represent 0 or 1 and satisfy 1≤m6+m7+m8≤3; and Si(OR 10) 4 wherein, R 10 represents an alkyl group having 1 to 6 carbon atoms; and mass ratio of the component to the component satisfies / ≥1, and of the constituting units derived from the general formula and the general formula in the component, mole ratio of the constituting unit derived from the general formula is 50% or more by mole. a silicon-containing compound obtained by a hydrolysis-condensation reaction of a mixture containing, at least, one or more hydrolysable silicon compound shown by the following general formula and one or more hydrolysable compound shown by the following general formula, R 1 m1 R 2 m2 R 3 m3 Si (4-m1-m2-m3) wherein, R represents a hydrocarbon group having 1 to 6 carbon atoms; at least one of R 1, R 2, and R 3 is an organic group selected from the groups shown by the following structural formulae, while the other is a hydrogen atom or a monovalent organic group having 1 to 30 carbon atoms; and m1, m2, and m3 represent 0 or 1 and satisfy 1≤m1+m2+m3≤3; U(OR 4) m4 (OR 5) m5 wherein, R 4 and R 5 represent an organic group having 1 to 30 carbon atoms, and m4+m5 is the same number as the number determined by valency of U; m4 and m5 represent an integer of 0 or more; and the U is an element belonging to groups of III, IV, or V in a periodic table except for carbon and silicon; a silicon-containing compound obtained by a hydrolysis-condensation reaction of a mixture containing, at least, one or more hydrolysable silicon compound shown by the following general formula and one or more hydrolysable silicon compound shown by the following general formula, R 6 m6 R 7 m7 R 8 m8 Si(OR 9) (4-m6-m7-m8) wherein, R 9 represents an alkyl group having 1 to 6 carbon atoms, and each R 6, R 7, and R 8 represents a hydrogen atom or a monovalent organic group having 1 to 30 carbon atoms; and m6, m7, and m8 represent 0 or 1 and satisfy 1≤m6+m7+m8≤3; and Si(OR 10) 4 wherein, R 10 represents an alkyl group having 1 to 6 carbon atoms; and mass ratio of the component to the component satisfies / ≥1, and of the constituting units derived from the general formula and the general formula in the component, mole ratio of the constituting unit derived from the general formula is 50% or more by mole.