Soybeans are used for various purposes as a major source of protein, carbohydrates, and fat. This study was conducted to investigate the component changes in protein, amino acid, and antioxidant substances with different sowing periods by soybean varieties, as climate warming accelerates in recent years. The content of isoflavone according to early sowing did not differ by sowing period. However, it was confirmed that the content of isoflavone was higher in functional soybean cultivars such as Cheongja-5 having blue color at seed inside, Pungsan and Sowon used soybean sprouts, and Jinyang without fishy smell. There was no significant difference in the changes in protein and amino acid content according to the sowing time by soybean cultivars. The protein and amino acid content by early sowing tended to be lower than that of timely sowing. In most varieties except for some varieties, the content of proline was the highest by early sowing, confirming the presence of stress due to early sowing.