A stimulus driver circuit for micro-stimulator used in implantable device was presented in this paper. For epileptic seizure control, the target of the driver was to output 30-μA stimulus currents when the electrode impedance varied within 20 and 200 kΩ. The driver, which consisted of output stage, control block, and adaptor, has been integrated in a single chip. The averaged power consumption of the stimulus driver was 0.24~0.56 mW under 800-Hz stimulation rate. Fabricated in a 0.35-μm 3.3-V/24-V CMOS process and applied to a closed-loop epileptic seizure monitoring and controlling system, the proposed design has been successfully verified in the experimental results of Long-Evans rats with epileptic seizures.