This paper proposes a mechanical cell contact system using a parylene rail filter (PRF) for in vitro analysis of connexin functions in cell-cell interaction. Connexin is a membrane protein that mediates interaction between contacting cells and allows small molecules to migrate between the cells. To study this molecular transfer and connexin function, cells must be maintained contact throughout experiments for days under the microscope. We reported a mechanical single liposome trap system with various advantages in MEMS2013 . In this present study, we developed a mechanical cell trap system that traps cells in contact with each other by using a micropatterned parylene rail. The number of trapped cells could be controlled by the length of the rail and the calcein dye transfer between the neighboring cells via connexin gap junctions (GJs) was successfully observed.