A palm-sized cell culture system "PASMA (Pressure Actuated Shapable Microwell Array)" has been developed for mass production of embryonic bodies (EBs) of human iPS cells. The key problem in increasing the number of microwells is the increase of the number of costly and large solenoid valves. In this report, we have introduced fluidic multiplexer circuits composed of pneumatically actuated normally-open valves and normally-closed valves. Thus, the number of microwells was increased from 100 to 256 despite decreasing the number of solenoid valves from 20 to 16. The results should accelerate the research and clinical application of PASMA for mass-production of high-quality EBs.