A cap includes a cap body and an atmosphere communication portion. The cap body comes into contact with and is pressed against a portion around an ink outlet of a nozzle head to form a main space between the cap body and the nozzle head. The atmosphere communication portion includes a ventilation hole, a sub-space, and a ventilation channel. The ventilation hole is open to the main space. The sub-space retains ink entering the ventilation hole. The ventilation channel allows the sub-space to be in communication with the atmosphere.