The present invention relates to a stimulation device (1) configured for interacting with an external body portion of a user, in particular the user's back. The interaction consists of exerting a mechanic action upon the user's body, 5 such as massage stimulation and/or skin scrubbing stimulation. For this purpose, the stimulation device (1) comprises a frame (50) provided with at least one upright element (2) extending along a longitudinal direction (L) preferably corresponding, in use, to a body height of the user, and stimulation means (4), slidably coupled with the upright element (2) according to the 10 longitudinal direction (L). Further, the stimulation device (1) is apt to be installed, in use, in a wall unit (100) for a shower cabin assembly (1000).