As fluid power sources mounted on practical and powerful micromachines such as in-pipe working micromachines using fluid power, micropumps having high power density are required. A piezoelectric micropump using resonance drive is proposed and developed. First, a large model of the proposed micropump is fabricated and the effectiveness of resonance drive is confirmed through basic experiments. Second, a micropump having the size of 9mm diameter and 10mm length for practical applications is fabricated. Next, frequency characteristics and load characteristics of the pressure-dependent flow rate are experimentally investigated with various structural parameters for the optimal design. Through those experiments, the optimal amounts of additional mass and valve thickness are experimentally obtained for stable and high performance of the micropump. The maximum flow rate of 80mm³/s, maximum pumping pressure of 0.32MPa and maximum power of 8.7mW are obtained at the driving frequency of 2.0kHz. Finally, the feasibility of developing the piezoelectric micropump using resonance drive is confirmed through comparisons of maximum power density among conventional micropumps.