A new chemistry in μm small volumes is being opened by utilizing laser and related microfabrication techniques. Reaction microfields were prepared by laser ablation, scanning tunneling electrochemical microscope, and area-selective chemical vapor deposition. Utilizing optical pressure of lasers, microparticles such as microcapsules, liquid droplets, polymer latex particles, and so on can be manipulated, and photochemistry and spectroscopy of a single trapped particle is made possible. Fluorescence characterization of a microcapsule, lasing of a polymer latex particle, laser preparation of a polymer gel particle, photochemical construction of microstructure from particles were demonstrated. Photochemical dynamics in μm dimension is discussed for liquid droplet and liquid layer near the solid wall. To demonstrate a high potential of laser microchemistry, some trials for constructing a microchemical system are described.