Blockage is a serious problem in practical use of microreactors, and detection of blockage is indispensable for their effective and stable operation. In this research, methods to locate channel blockage and estimate the degree of blockage were derived based on a simple pressure balance model of a microreactor. The proposed methods use the correlations between the pressure distribution data calculated by the pressure balance model and the actual pressure distribution data when blockage occurs. The results of computer simulation using fluid dynamics simulation software showed that the proposed methods can identify the blockage location and estimate the degree of blockage. The accuracy depends on the number and configuration of pressure sensors.