As of 2021, the Japanese construction company Kongō Gumi, founded in 578 C.E is the oldest existing company worldwide, and has operated for around 1.443 years.
As well as having the oldest company in the world, Japan is also home to the second to fifth-oldest companies, with three of them (Nisiyama Onsen Keiunkan, Koman, and Hōshi Ryokan) being hotels.
The oldest company outside of Japan is an Austrian inn called Stiftskeller St. Peter, operating within the walls of a church in Salzburg since 803 C.E. (Source Statista)