A supply part for supplying resin, a smoothing part for smoothing the resin, and an objective lens for exposing the smoothed resin to light are provided in separate positions within substantially the same horizontal plane, and a modeling part is movable by a horizontal drive mechanism under the three above-mentioned components. For processing in the three above-mentioned components, the modeling part is moved to positions immediately under the three above-mentioned components in order by the horizontal drive mechanism. Thus, the modeling part is brought as close to the three above-mentioned components as possible for processing. The exposure is performed, with the objective lens fixed to a base body. Exposure light is focused onto a resin layer on a modeling base, and the light reflected from the resin layer is received by the objective lens, directed by a beam splitter toward an image surface optical system and received as an image by a CCD camera. During the exposure, the directed exposure light serves as illumination light which enables an operator to check whether current focus is achieved on the surface of the resin layer. During a time interval between the completion of the exposure of the resin layer to light and the execution of the exposure of the next resin layer to light, the fine adjustment of the vertical position of a stage is made, whereby the fine adjustment of the focus position is made in accordance with the result of observation using a monitor. This prevents the decrease in modeling accuracy for the subsequent resin layers, thereby to hold the modeling accuracy for the entire model higher, thereby improving the yield and productivity of models. These provide a stereolithography apparatus which attains a resin layer thickness of 10 .mu.m and an exposure resolution of 2 .mu.m and is preferred for micromachining.