Recently, many efforts have been made to investigate the cell stretch response through focal adhesions, which are usually utilized by cells cultured on elastic materials. However, not all stretch sensing is mediated through focal adhesions but from cell-cell contacts such as adherence junctions. To unveil the details of the stretch-sensing mechanism through cellcell contacts, we developed a cell-sheet extension device for visualizing dynamic changes of individual living cells induced by external mechanical stretch. A cell-sheet is an ideal observation object, as it can be comprised merely of cells without any mechanical influences from external matrices while maintaining normal cell-cell adhesions as in the in vivo situation. Two microfluidic extension devices were designed and fabricated using a silicone elastomer, which were capable of extending a cell-sheet made from Caco-2 cells up to 1.3- and 1.5-fold from its original state. Based on the obtained results, we expected that such cell-sheet extension systems can be useful tools for understanding the mechanisms of cellular stretch sensing through cell-cell contacts in living cells.