The Sega System 1 is an arcade platform officially debuted by Sega in 1983, based on earlier 1982 prototype hardware. It is a Z80-based platform and the first in the decade-long "System" series of arcade boards.

The System 1 was a relatively popular arcade board for its day, supported not only by Sega, but by Japanese developers Coreland and VIC Tokai between 1983 and 1987. In 1985 it was succeeded by the slightly more powerful Sega System 2 board, though new games were released for both systems concurrently. Many of the System 1's games were ported to the SG-1000 and Sega Master System consoles.