There is provided a tank system including a tank and a liquid injection container. The tank has a liquid storage chamber; and a cylindrical wall extending from an outer wall in a first direction. The tank is formed with inlet and outlet ports each communicating the liquid storage chamber with the outside of the tank. The liquid injection container includes: a liquid storing portion; a liquid discharging portion; an arm; and a craw. The cylindrical wall has: a first portion, a second portion located between the first portion and the outer wall and having outer diameter smaller than that of the first portion, and a connecting surface connecting the outer circumferential surface of the first portion to that of the second portion. The craw contacts the connecting surface of the cylindrical wall toward the first direction in a state that the liquid discharging portion is inserted into the inlet port.