In recent years, an interest in micro devices and systems has increased rapidly, and this trend is expected to continue for years to come. Gaseous flow through and within such devices is a principal consideration in many applications, and its understanding can be crucial for optimization of performance. Detailed understanding of fundamental physical processes on these small scales is hampered by the lack of suitable quantitative measurement tools (pressure and temperature sensors, etc.). Pressure-sensitive paint (PSP) is one of the options for global distribution measurement in MEMS devices. PSP is a "molecular sensor," and has an enough resolution for MEMS. In this paper, we demonstrate the use of PSP for quantitative measurement of pressure distribution in supersonic micronozzles of the nozzle throat 250μm, such as those that might be employed for flow control and/or small satellite orbit maintenance. And we compare the experimental result with numerical simulation by the conventional Reynolds-averaged Navier-Stokes equations in the three-dimensional space.