To solve the problem in the portability of a conventional portable printer because of the size, the weight and connection by a cable, and eliminate printing failures of an ink jet printer when receiving vibrations and shocks.

A printer part 3 is attached to a connector of a lower part of a portable phone 2 thereby executing printing together with the portable phone 2. A cap part 4 constituted integrally of a cap, a pump, an ink tank and a waste ink tank is set, which is made detachable to the printer part 3. Bubbles in a printing head are discharged every time the cap part 4 is detached.