This letter presents experimental results of an efficient TE-TM mode converter using a Z-propagation LiNbO3 waveguide. A three-section electrode structure with 10 mm length allows us to control mode coupling and phase matching independently by two different applied voltages. The drive voltage is only 5.2 V with the mode conversion efficiency of 98% when the phase matching condition is satisfied by the voltage tuning. This mode converter is also free from optical damage because of the use of Z-propagation LiNbO3.