Ink cartridge

An ink cartridge includes a cartridge body, an ink supply portion and an air communication portion provided at the cartridge body, a block member and a slider. The air communication portion has an inner peripheral wall defining an air passage, and a communication port for allowing communication between an ink chamber and the air passage. The block member moves from a first position to a second position by contact with the slider sliding in a sliding direction to block and open the air passage. The slider includes: a first cylindrical portion having an upstream through-hole penetrating therethrough; a second cylindrical portion having a downstream through-hole penetrating therethrough and communicating with the upstream through-hole; and a semipermeable membrane closing the upstream through-hole. The slider has a contact portion in close contact with the inner peripheral wall at a position upstream of the block member at the first position in the sliding direction.