A coupled torsion beam axle type suspension system (CTBA) may include trailing arms respectively coupled to opposite ends of a torsion beam, and a vehicle body-engaging unit provided in a front end portion of each of the trailing arm and engaging the each of the trailing arms to a vehicle body, wherein each vehicle body-engaging unit includes a trailing arm bush that may be coupled to a front end portion of the trailing arm, a rotation link disposed in front of the trailing arm bush and engaged thereto in a width direction of a vehicle, a slider rotatably connected to a front end portion of the rotation link, and slidable along a length direction of the vehicle body, and a connection link pivotally connecting an outer end portion of the rotation link and the vehicle body.