We report on a novel microdevice to tune the curvature of a cell-adhering surface by controlling the air-pressure and micro-slit. Human aortic smooth muscle cells were cultured on demi-cylindrical concaves formed on a microdevice. Their shape-adapting behavior could be tracked when the groove direction was changed to the orthogonal direction. This microdevice demonstrated live observation of cells responding to dynamic changes of the anisotropic curvature of the adhering surface and could serve as a new platform to pursue mechanobiology on curved surfaces.