This study presents a three-dimensional inverted pendulum system using three symmetrically arranged vertical reaction wheels for balance control and an additional horizontal reaction wheel for direction control. The dynamics of the inverted pendulum system is modeled using the Euler–Lagrange equation, and the model is linearized for controller design. To verify the control performance of the system, a linear quadratic regulator controller is designed for the balance control and a proportional and derivative controller for the direction control. The performance of the proposed control system is verified through simulations. Based on the simulation results, an actual inverted pendulum is constructed, and the control for the system is experimentally validated.