A single-motor massager has a housing, a carriage and a lead threaded rod mounted in the housing, a guiding assembly, two transmission assemblies and a driving assembly mounted in the carriage, and two massage assemblies respectively driven by the transmission assemblies. The lead threaded rod has a right-handed thread and a left-handed thread so the carriage moves back and forth along the lead threaded rod and the massage assemblies can massage a large area of an operators back. One of the transmission assembly has a one-way bearing so the carriage is able to stop at any position of the lead threaded rod and the massage assemblies are able to focus on a massage function at a specific position.
