According to Wikipedia List of oldest corporations, the world’s oldest corporation is: 578 (year) Kongō Gumi, in Japan, in Construction business.
The Wikipedia page for that business adds:
Kongō Gumi Co., Ltd. (株式会社金剛組 Kabushiki Gaisha Kongō Gumi) is a Japanese construction company which was the world’s oldest continuously ongoing independent company, operating for over 1,400 years until it was absorbed as a subsidiary of Takamatsu in 2006.[1][2]
Related Salon.com link: Why are so many of the world’s oldest companies from Japan?