A method for producing an objective substance, the method comprising the following step: producing the objective substance by using a microorganism having an ability to produce the objective substance, wherein the microorganism is a bacterium belonging to the family Enterobacteriaceae, such as a bacterium belonging to the genus Escherichia, such as Escherichia coli; or wherein the microorganism is a coryneform bacterium, such as a bacterium belonging to the genus Corynebacterium, such as Corynebacterium glutamicum; or wherein the microorganism is yeast, wherein the microorganism has been modified so that the activity of S-adenosyl-L-homocysteine hydrolase is increased as compared with a non-modified strain, wherein the activity of S-adenosyl-L-homocysteine hydrolase is increased by increasing the expression of a gene encoding S-adenosyl-L-homocysteine hydrolase, wherein the expression of the gene encoding S-adenosyl-L-homocysteine hydrolase is increased by modifying an expression control sequence of the gene, wherein the S-adenosyl-L-homocysteine hydrolase is a protein encoded by sahH gene, wherein said sahH gene encodes a protein selected from the group consisting of: (a) a protein comprising the amino acid sequence of SEQ ID NO: 145, (b) a protein comprising the amino acid sequence of SEQ ID NO: 145 but that includes substitution, deletion, insertion, and/or addition of 1 to 10 amino acid residues, and wherein said protein has S-adenosyl-L-homocysteine hydrolase activity, and (c) a protein comprising an amino acid sequence having an identity of 90% or higher to the amino acid sequence of SEQ ID NO: 145, and wherein said protein has S-adenosyl-L-homocysteine hydrolase activity, and wherein the objective substance is selected from vanillin or vanillic acid. producing the objective substance by using a microorganism having an ability to produce the objective substance, wherein the microorganism is a bacterium belonging to the family Enterobacteriaceae, such as a bacterium belonging to the genus Escherichia, such as Escherichia coli; or wherein the microorganism is a coryneform bacterium, such as a bacterium belonging to the genus Corynebacterium, such as Corynebacterium glutamicum; or wherein the microorganism is yeast, wherein the microorganism has been modified so that the activity of S-adenosyl-L-homocysteine hydrolase is increased as compared with a non-modified strain, wherein the activity of S-adenosyl-L-homocysteine hydrolase is increased by increasing the expression of a gene encoding S-adenosyl-L-homocysteine hydrolase, wherein the expression of the gene encoding S-adenosyl-L-homocysteine hydrolase is increased by modifying an expression control sequence of the gene, wherein the S-adenosyl-L-homocysteine hydrolase is a protein encoded by sahH gene, wherein said sahH gene encodes a protein selected from the group consisting of: (a) a protein comprising the amino acid sequence of SEQ ID NO: 145, (b) a protein comprising the amino acid sequence of SEQ ID NO: 145 but that includes substitution, deletion, insertion, and/or addition of 1 to 10 amino acid residues, and wherein said protein has S-adenosyl-L-homocysteine hydrolase activity, and (c) a protein comprising an amino acid sequence having an identity of 90% or higher to the amino acid sequence of SEQ ID NO: 145, and wherein said protein has S-adenosyl-L-homocysteine hydrolase activity, and (a) a protein comprising the amino acid sequence of SEQ ID NO: 145, (b) a protein comprising the amino acid sequence of SEQ ID NO: 145 but that includes substitution, deletion, insertion, and/or addition of 1 to 10 amino acid residues, and wherein said protein has S-adenosyl-L-homocysteine hydrolase activity, and (c) a protein comprising an amino acid sequence having an identity of 90% or higher to the amino acid sequence of SEQ ID NO: 145, and wherein said protein has S-adenosyl-L-homocysteine hydrolase activity, and wherein the objective substance is selected from vanillin or vanillic acid.