A micromirror actuator includes: a substrate; spring units elastically supported by protrusion formed on the substrate; a micromirror connected to the spring units and formed to be capable of rotating; trenches formed in the substrate at either side of the protrusions to correspond to the surface of the micromirror; and lower electrodes formed in each of the trenches. Accordingly, it is possible to expand the range of the driving angle of the micromirror with the use of a lower voltage.