A 50 μm x 50 μm aluminum micromirror array has been fabricated using surface-micromachining technology. 50 x 50 micromirrors are arrayed two dimensionally. A micromirror plate is supported by a vertical spring structure which is placed underneath the mirror plate. With this structure, when the mirror plates reflect light, the micromirror array can have a large effective reflecting area. Only one mask and one shadow evaporation process are used in the fabrication of the vertical springs. The experimental electromechanical characteristics of the fabricated micromirror reveal that the downward threshold voltage is 8 V, the step response time is 17 μs when 29 V step voltage is applied, and the resonance frequency is 11 kHz. No mechanical failure is found until after 200 million cycles of one-directional operation.