A flexible electronic device is disclosed. The flexible electronic device includes a protruding unit, a flexible substrate and a plurality of sensing units. The flexible substrate is disposed on the protruding unit and has a deformation region corresponding to the protruding unit. The sensing units are disposed on the flexible substrate, and at least one of the sensing units is overlapped with the deformation region. A ratio of an area of the deformation region to an area of one of the at least one of the sensing units is greater than or equal to 1.4 and less than or equal to 2222.