A medical apparatus for standing aid includes a backrest (4) that has at least one side thereof provided with a crank rocker mechanism that includes a crank mechanism (1), a triangle linkage mechanism (2), and a rocker mechanism (3), the crank mechanism (1) is rotatably connected to the triangle linkage mechanism (2) such that an included angle between a second driven link (BE) of the triangle linkage mechanism (2) and the crank mechanism (1) is always smaller than 90°, and the crank mechanism (1) driving the triangle linkage mechanism (2), the rocker mechanism (3) and the backrest (4) connected to the triangle linkage mechanism to perform interactive movement repeatedly along a predetermined curve trajectory in response to a driving force from a drive effect of a driving unit (100), so that the backrest (4) connected to the second driven link (BE) assists a trainee in standing up repeatedly by obliquely supporting the trainee's waist.
