A lightweight portable device is provided to impart continuous passive motion to a user's shoulder. The device causes abduction and adduction and has the option of causing simultaneous rotation as well through use of a single actuator. The base of the device is curved to fit against a lateral portion of the user's torso and the device is held in position by a harness. An upper arm support is pivotally connected to and extends laterally from the base. A linear actuator extends between and is linked to the upper arm support and the base to cause abduction and adduction of the arm. A forearm support which is pivotally connected to the upper arm support and is also angularly adjustable relative to the upper arm support is linked to the base to cause rotation of the forearm support as the upper arm support is pivoted. The range of rotation can be varied or eliminated. The degree and speed of abduction and adduction can also be varied. The device is contained in a housing having a chamber with an extendable, two-part cover so that the operating mechansim is concealed.