Abstract: The printing head 50 includes an insulative member 52 in which pluralities of apertures 56 are formed. Doughnut-like first and second electrodes 68 and 70 are disposed around the aperture 56. Pulse voltages V1(P) and V2(P) both having a certain polarity opposite to that of the toner particles are applied to the first and second electrodes 68 and 70, energizing the toner particles 38 to afford propelling thereof. Subsequently, a voltage V2(B) having the same polarity as the charged toner particles 38 is applied to the second electrode 70, forcing radially inwardly to converge the propelling toner particles 38 in the aperture 56. This ensures that a dot and an image both having clear contour can be formed on the sheet 8.