A liquid ejecting system includes a liquid ejecting apparatus, a containing unit configured to contain a liquid, and a liquid supply tube configured to supply the liquid from the containing unit to the liquid ejecting apparatus. The liquid ejecting apparatus includes a first casing and a second casing that opposes the first casing. The containing unit includes a third casing and a fourth casing that opposes the third casing. The first casing has a first penetration hole. The second casing has a second penetration hole that overlaps with the first penetration hole. The fourth casing has a first protruding section. The containing unit is fixed to the liquid ejecting apparatus in a state where the first protruding section is inserted into the first penetration hole and the second penetration hole.