The present invention provides a stand assist device, which comprises a first frame body, a second frame body, a first supporting member, a second supporting member, a power unit； the first frame body is having a first pivoting part and a first guiding portion； the second frame body is having a second pivoting part and a second guiding portion； the front side of the first supporting member is pivotally connected to the first pivoting part and the rear side of the first supporting member is movably disposed on the second guiding portion； the front side of the second supporting member is pivotally connected to the second pivoting part and the rear side of the second supporting member is movably disposed on the first guiding portion； the power unit provides a power to relatively move or swing the first frame body, the second frame body, wherein two of them swing relatively, thereby providing a vertical upward supporting force, which makes the user more stable and comfortable in the process of changing from a sitting posture to a standing posture, and then giving a tilting upward force to assist the user to stand.
