The thermal annealing effect on the compressive residual stress has been presented in thin diamond-like carbon (DLC) film on Si substrate. Annealing experiments were carried out with Rapid Thermal Procedure system at from 200 to 600 degrees C, and the variation of residual stress with annealing temperature was investigated by in-situ stress measurement system. The stress reduction occurs as annealing temperature increases, while the change of chemical structure of DLC film is not significantly changed with observation by Raman spectrometer. The elastic modulus and hardness are not deteriorated when annealing temperature is controlled at less than 400 degree of Celsius, where the residual stress is apparently reduced.