Recently, the gear breakage and the noise due to the repetitive impact load in the lightly loaded gear train became one of big problems. For the theoretical analysis of this problem, actual contact characteristics of a pair of gear under lightly loaded is necessary. In this paper, the exact contact characteristics were obtained experimentally. Actually we obtained, spring characteristics and damping characteristics for the ideal condition, misalinement condition and double flank meshing condition. The result of lightly loaded gear pair has nonlinearity and the smaller values of contact characteristics compare with gears which used under heavy load for transmit power.