This paper presents a novel means of introducing conductive pyrolyzed polymer structures into a μTAS platform. Insulation structures of polymer materials can be transformed into conductive structures through pyrolysis, and MEMS structures consisting of pyrolyzed polymer can be formed by a dual process of micromachining and pyrolysis. This work focuses on gate type sensing by a three-dimensional pyrolyzed polymer electrode. The three-dimensional SU-8 original structure was micromachined by multi-angle inclined lithography. Three-dimensional structures of pyrolyzed SU-8, which have meshes of 10 μm × 20 μm in dimension, could be obtained by pyrolysis in N2 atmosphere. Furthermore, the structures were integrated into the SU-8 fluidic channel with the 100 μm in height and 200 μm in width by a post-pyrolysis process. We will demonstrate the cross sectional sensing in electrochemical detection by making the best use of the three-dimensional mesh structure to overcome the restriction of planar electrode.