A rubber composition for a tire, comprising: a diene polymer; silica; and a compound represented by the formula shown below, the diene polymer being a modified diene polymer obtained by reacting a compound and a compound, and the compound represented by the formula being present in an amount of 5 to 23 parts by mass relative to 100 parts by mass of a rubber component, wherein the compound is an active alkali metal-terminated conjugated diene polymer obtained by polymerizing a conjugated diene monomer alone or with an aromatic vinyl monomer in the presence of a compound as a polymerization initiator; the compound is a modifying agent containing a functional group, with the modifying agent being a compound represented by the following formula: wherein R 5 and R 6 are the same as or different from each other and each represent a branched or unbranched C 1-10 hydrocarbon group which may contain at least one selected from the group consisting of an ether group and a tertiary amine group; R 7 and R 8 are the same as or different from each other and each represent a hydrogen atom, or a branched or unbranched C 1-20 hydrocarbon group which may contain at least one selected from the group consisting of an ether group and a tertiary amine group; R 9 represents a branched or unbranched C 1-20 hydrocarbon group which may contain at least one selected from the group consisting of an ether group, a tertiary amine group, an epoxy group, a carbonyl group, and a halogen group; and n represents an integer of 1 to 6; the compound is a chemical species obtained by reacting an organic alkali metal compound with a compound represented by the following formula: wherein R 1 and R 2 are the same as or different from each other and each represent a hydrogen atom, a branched or unbranched alkyl group, a branched or unbranched aryl group, a branched or unbranched alkoxy group, a branched or unbranched silyloxy group, a branched or unbranched acetal group, a carboxy group, a mercapto group, or a derivative thereof, and A represents a branched or unbranched alkylene group, a branched or unbranched arylene group, or a derivative thereof; and the formula is: R 3 -S-S-Y-S-S-R 4 wherein Y represents a branched or unbranched C 2-10 alkylene group, and R 3 and R 4 are the same as or different from each other and each represent a monovalent branched or unbranched organic group containing a nitrogen atom. a diene polymer; silica; and a compound represented by the formula shown below, the diene polymer being a modified diene polymer obtained by reacting a compound and a compound, and the compound represented by the formula being present in an amount of 5 to 23 parts by mass relative to 100 parts by mass of a rubber component, wherein the compound is an active alkali metal-terminated conjugated diene polymer obtained by polymerizing a conjugated diene monomer alone or with an aromatic vinyl monomer in the presence of a compound as a polymerization initiator; the compound is a modifying agent containing a functional group, with the modifying agent being a compound represented by the following formula: wherein R 5 and R 6 are the same as or different from each other and each represent a branched or unbranched C 1-10 hydrocarbon group which may contain at least one selected from the group consisting of an ether group and a tertiary amine group; R 7 and R 8 are the same as or different from each other and each represent a hydrogen atom, or a branched or unbranched C 1-20 hydrocarbon group which may contain at least one selected from the group consisting of an ether group and a tertiary amine group; R 9 represents a branched or unbranched C 1-20 hydrocarbon group which may contain at least one selected from the group consisting of an ether group, a tertiary amine group, an epoxy group, a carbonyl group, and a halogen group; and n represents an integer of 1 to 6; the compound is a chemical species obtained by reacting an organic alkali metal compound with a compound represented by the following formula: wherein R 1 and R 2 are the same as or different from each other and each represent a hydrogen atom, a branched or unbranched alkyl group, a branched or unbranched aryl group, a branched or unbranched alkoxy group, a branched or unbranched silyloxy group, a branched or unbranched acetal group, a carboxy group, a mercapto group, or a derivative thereof, and A represents a branched or unbranched alkylene group, a branched or unbranched arylene group, or a derivative thereof; and the formula is: R 3 -S-S-Y-S-S-R 4 wherein Y represents a branched or unbranched C 2-10 alkylene group, and R 3 and R 4 are the same as or different from each other and each represent a monovalent branched or unbranched organic group containing a nitrogen atom.