Provided are a method for efficiently manufacturing a nitrogen-containing compound, which is used for manufacturing a treatment agent for integrin-related diseases, or a salt thereof and a manufacturing intermediate of the compound or a salt thereof. A method for manufacturing a novel nitrogen-containing compound or a salt thereof includes (1) a step of obtaining a compound represented by Formula [10] or a salt thereof through an amidation reaction； and (2) a step of deprotecting the compound represented by Formula [10] or a salt thereof.
