Is it possible to distinguish cells with minimally-invasive method according to the characteristics of cells when moving through the flow path in vitro? A microflow channel with 45 degrees diagonal microgrooves against the mainstream direction has been manufactured by photolithography technique. The flow path between the two transparent PDMS (polydimethylsiloxane) disks (0.05 mm high, 1 mm wide, and 25 mm long) has a rectangular microgroove (4.5 μm deep, 0.2 mm long) at the bottom with variations in groove widths (0.03 mm, 0.04 mm, and 0.05 mm). The deformation and direction change of floating mouse-myoblasts (C2C12) during passage over the microgroove were measured. The experimental result shows that the change in angle tends to be smaller for cells with larger shape changes in the groove. This method may be applicable to classification by cell deformability.