We propose a newly designed plate-type reactor, which is in the concept of an assembly-type microreactor and can be varied in the size of the internal reaction space of the depth of catalytic bed or the width of the flow channel by replacement of assembled parts, and where it is possible to set powder catalysts, d p < 0.3 x 10(-3) m, without of washcoat or electroless plating process. Using the plate-type reactor with powder catalysts, we confirmed the advantage of the reactor under dry reforming of methane. Under CH4/CO2/He = 1/2/5 at 773 K as a lean methane condition, the plate-type reactor could assume inherent catalyst performance, i.e., the performance of reaction controlled conditions, lower pressure drop and/or friction factor than that of a packed bed reactor, even with coarse particle catalysts at the nearly same or higher methane conversion. Further, these trends became much more pronounced under CH4/CO2/He = 1/1/0 at 773 K as a rich methane condition. These results mean that the plate-type reactor allows for prolonged operation time until channel blockage due to carbon deposition. Moreover, it is suggested that the plate-type reactor can undergo more optimization by replacement of different sized reactor parts to avoid diffusion controlled condition.