An optimal model-free controller and a linear controller are designed and applied to a horizontal magnetic micromanipulator for controlling microparticles in a liquid environment. An input-output relation based model for the magnetic micromanipulator is obtained, verified, and used in the analysis of controllers. A model-free linear controller is designed using the offset current approach. An optimal nonlinear controller based on Karush-Kuhn-Tucker conditions is designed and then modified to produce smooth control signals. Experimental results are provided to show the efficiency and feasibility of the proposed controllers. The model-free controllers yield short settling time and zero steady-state error in the control of magnetic microparticles.