This paper describes charging and deflection characteristics of a binary multi-nozzle ink jet printer. In a binary printer, ink drops are selectively deflected by applying a charge to them, while uncharged drops proceed in a straight line to form the part of characters. The printer used in our experiment has eight nozzles, 55µm in diameter and on 0.5 mm centers. Charging electrode slot width is 0.3 mm. Drop frequency is 40 kHz. Drop frequency is divided into printing frequency by 16 so that a moderate printing speed is obtained. The charge electrode array is positioned with respect to a nozzle array so that the drop formation occurs within a certain region inside the charge electrode slots. Then no crosstalk between the adjoining electrodes has been observed and the induced charge by the previously charged drop can be neglected. The deflection condithion, for defect-free prints, is such that the charged drops are collected into a catcher whereas the charged drops do not merge with the uncharged drops. The charging voltage and the separation between the undeflected ink streams and the deflection plated are important parameters. Experimentally a sufficient amount of deflection has been obtained by the image force of the charged drops without the use of a high deflection voltage.