A method for producing a terminal-modified polybutadiene or terminal-modified hydrogenated polybutadiene having a number average molecular weight of 500 to 10,000 and represented by formula: (wherein R 1 represents a hydrogen atom or a methyl group, R 2 represents a C1 to C10 alkylene group having a straight chain or a branched chain, a C3 to C8 cycloalkylene group optionally having a C1 to C6 alkyl group as a substituent, or a combined group thereof, R 3 represents a C1 to C10 alkylene group having a straight chain or a branched chain; a C3 to C8 cycloalkylene group optionally having a C1 to C6 alkyl group as a substituent; an arylene group optionally having a halogen atom, a C1 to C6 alkyl group, or a C1 to C6 alkoxy group as a substituent; a heteroarylene group optionally having a halogen atom, a C1 to C6 alkyl group, or a C1 to C6 alkoxy group as a substituent; or a combined group thereof, m represents 1 or 2, and PB represents a polymer chain obtained by polymerizing butadiene, or a polymer chain obtained by hydrogenating the polymer chain), comprising reacting: - an acrylate or methacrylate represented by formula: (wherein R 1 and R 2 represent the same meaning as described above), - a diisocyanate compound represented by formula: (wherein R 3 represents the same meaning as described above), and - a polybutadiene or hydrogenated polybutadiene having a hydroxyl group at a polymer terminal, represented by formula: PB(̵OH) m (wherein PB and m represent the same meaning as described above), in the presence of at least one selected from: - an organoaluminum compound represented by formula: (wherein R 11, R 12, R 13 and R 14 each independently represent a C1 to C30 alkyl group having a straight chain or a branched chain), and - an organozinc compound represented by formula: (wherein each R 21 represents a C1 to C30 alkyl group having a straight chain or a branched chain, and is the same or different), wherein i) the amount of the acrylate and methacrylate compounds represented by formula is in the range of 0.2 to 2 times moles with respect to the hydroxyl group of the polybutadiene or hydrogenated polybutadiene having a hydroxyl group at a polymer terminal represented by formula, ii) the amount of the diisocyanate compound represented by formula is in the range of 0.2 to 2 times moles with respect to the hydroxyl group of the polybutadiene or hydrogenated polybutadiene having a hydroxyl group at a polymer terminal represented by formula, and iii) the amount of the organoaluminum compound represented by formula or organozinc compound represented by formula is 0.001 parts by weight to 10 parts by weight with respect to 100 parts by weight of the terminal-modified polybutadiene or the terminal-modified hydrogenated polybutadiene represented by formula. - an acrylate or methacrylate represented by formula: (wherein R 1 and R 2 represent the same meaning as described above), - a diisocyanate compound represented by formula: (wherein R 3 represents the same meaning as described above), and - a polybutadiene or hydrogenated polybutadiene having a hydroxyl group at a polymer terminal, represented by formula: PB(̵OH) m (wherein PB and m represent the same meaning as described above), - an organoaluminum compound represented by formula: (wherein R 11, R 12, R 13 and R 14 each independently represent a C1 to C30 alkyl group having a straight chain or a branched chain), and - an organozinc compound represented by formula: (wherein each R 21 represents a C1 to C30 alkyl group having a straight chain or a branched chain, and is the same or different), i) the amount of the acrylate and methacrylate compounds represented by formula is in the range of 0.2 to 2 times moles with respect to the hydroxyl group of the polybutadiene or hydrogenated polybutadiene having a hydroxyl group at a polymer terminal represented by formula, ii) the amount of the diisocyanate compound represented by formula is in the range of 0.2 to 2 times moles with respect to the hydroxyl group of the polybutadiene or hydrogenated polybutadiene having a hydroxyl group at a polymer terminal represented by formula, and iii) the amount of the organoaluminum compound represented by formula or organozinc compound represented by formula is 0.001 parts by weight to 10 parts by weight with respect to 100 parts by weight of the terminal-modified polybutadiene or the terminal-modified hydrogenated polybutadiene represented by formula.