We present a miniature direct methanol fuel cell (micro-DMFC) using platinumsputtered microcolumn electrodes with a built-in fuel chamber to improve power density. We designed and fabricated both microcolumn and planar electrodes with an identical projective area of 4.5 mm×4.5 mm. In an experimental study, we performed a single-cell test to compare the microcolumn electrode with the planar electrode. In the single-cell test, the micro-DMFC with microcolumn electrodes showed a maximum power of 24.8 µW (122.4 µW/cm2) at 0.65 V, while the micro-DMFC with planar electrodes showed a maximum power of 1.1 µW (5.6 µW/cm2) at a voltage of 0.08 V. The micro-DMFC with microcolumn electrodes showed a constant maximum power of 122.4 µW/cm2 over 40 min. The micro-DMFC with microcolumn electrodes had a maximum power density 22 times higher than that of the micro-DMFC with planar electrodes in a single-cell test.