We have designed, fabricated and characterized a micromirror array for protein microarray fabrication that has a simple structure, and the straightforward fabrication process for the mirror will allow the use of low-cost mirrors in protein pattern applications. The characteristics of an exposure system utilizing the micromirror array have been demonstrated by means of an experiment employing a photoresist that is in general use in the semiconductor industry. The micromirror dimensions were 54 × 54 μm², with a 30 μm separation between mirrors, and a 5.5 μm gap from the bottom electrode so that the mirror had an approximately 10° deflection angle. The size and separation of the mirror were designed in consideration of the protein pattern size and pitch, in contrast with the commercial Texas Instruments Digital Light Processor, which is utilized in the components of projection display systems. The exposure system combined with the micromirror has been used in the photochemical synthesis of chemical ligands via protein immobilization on a chip. Several photosynthesis experiments for peptide array synthesis have been carried out using the micromirror array. Parallel experiments on photochemical ligand synthesis on a chip can easily be performed in the laboratory using this exposure system.