The present invention relates to a method of manufacturing fermented soybeans having increased gamma-aminobutyric acid (GABA) content, and more particularly, a method of manufacturing fermented soybeans having increased gamma-aminobutyric acid content which comprises the steps of: adding lactobacillus having glutamate decarboxylase (GAD) activity and glutamate (MSG) to soybeans; grinding and molding the mixture; and spraying starch powder mixed with seed malt onto the surface of the molded mixture. The present invention can provide a method of manufacturing fermented soybeans including GABA, which has been known to accelerate sodium ion discharge through urine, so that it may lower blood pressure hypertension which may be caused from excessive consumption of salts to prevent and can produce functional paste foods satisfying people's taste and desire for health.