This paper discusses the active vibration control of a smart beam having piezoelectric fibers with metal cores where they function as sensors and actuators in the CFRP composite [1]. However, multiple piezoelectric fibers are embedded to gain more actuator power, creating unevenness in the actuator outputs. Unevenness of the actuator outputs degrades the control performance when all fibers are driven with a single piezo amplifier. Hence, we designed a controller using synthesis considering the actuator unevenness for the new smart beam embedded thirty piezoelectric fibers. First, we established a finite element model of a cantilever beam embedded with the piezoelectric fiber and a reduced-order model for controller design. We next transformed the reducedorder model into a linear fractional transformation (LFT) representation considering the actuator unevenness as the perturbation. Next, using the controller designed by using μsynthesis, control experiments were carried out. The experimental results demonstrated that the piezoelectric fiber with a metal core functions effectively as a sensor or actuator for active vibration control, and our control design method resolved the actuator unevenness issue.