This paper considers the problem of trajectory tracking control of an omnidirectional mobile root. First, the dynamic model of an omnidirectional mobile robot is derived to facilitate the control design. In the controller design, state feedback is used to linearize the system. Based on the linearized system, integral sliding mode control is then designed for trajectory tracking control. This control strategy is robust to model uncertainties and exogenous disturbances. The designed control laws are implemented and tested on an experimental setup. The effectiveness of the control scheme is demonstrated through simulation and experimental studies, and is compared with the well-tuned PID control. It is shown that the control system with the integral sliding mode controller has better tracking performance.