PURPOSE: To eliminate the generation of ink clogging even when an ink jet printer is stopped over a long period of time by providing a nozzle cap between a nozzle and a charge electrode as the guide at the time of the attachment of a charge electrode part.

CONSTITUTION: In the case of a charge control type ink jet printer, since a charge electrode 3 is attached at the position separated from the leading end of a nozzle by about 1-3mm, there is no sufficient space at the leading end part of the nozzle 2 and it is necessary to attach the nozzle cap by utilizing this restricted gap. The nozzle cap 10 has a horizontal U-shape and the charge electrode 3 is used as a guide to be pressed from above so as to be inserted in the recessed part of the nozzle cap 10 to be attached to the nozzle cap 10. The material of the nozzle cap 10 is pref. fluoroplastic or ethylene/propylene rubber. The nozzle cap 10 can be certainly attached by sufficiently inserting the nozzle cap 10 until the lower end surface thereof comes into contact with a substrate.