We have fabricated high-performance organic thin-film transistors with top contact geometry using silver source and drain electrodes that are directly patterned on pentacene film by inkjet printing. Ink droplets containing Ag nanoparticles were ejected from inkjet nozzles. By controlling wave forms applied to piezoelectric actuators in these nozzles, the volume of the droplets can be changed from 17 to 1.4 pl. When the volume of the droplets is reduced, dc characteristics of manufactured transistors are improved significantly. The transistors manufactured with droplets of 1.4 pl exhibit a mobility of 0.3cm2/Vs and an on-off current ratio that exceeding 106.