There is provided a protective cap configured to be installed into a liquid cartridge installation section having a liquid supply tube in fluid connection with a recording head for jetting a liquid via a flexible tube. The protective cap includes: an chamber defined by a case in a liquid-tight manner; a liquid absorbing member filled in the chamber; a connecting portion having a connecting channel in communication with the chamber and configured to be connected with the liquid supply tube; and an atmosphere communication portion via which the chamber communicates an outside of the case.