Delay in germination of forest tree seeds has given rise to a difficulty for nursery practice. The experiments described here were designed to clarify the mechanism of dormancy causing such a delay and improve practical techniques. The results obtained showed that each of five pretreatments, based on moist low-temperature method, was effective on hastening the germination of Pinus koraiensis seeds and above all the combined method of “2°C. (1.5 months) -25°C. (1.5 months) -2°C. (2 months)” the most effective. Rudimentary and dormant embryos in the resting seeds enlarged under some pretreatments. The time for this enlargement could be shortened by exposing to low temperature under moist condition. In the resting seeds sucrose, raffinose, and aslight amount of starch are present, but stachyose is absent. During pretreatments, glucose and stachyose appeared, while sucrose and raffinose decreased. Moreover, fructose was found on the chromatogram at the stage III of M1, and stachyose in the seeds of M3 had almost disappeared at the stage of IV. The amount of starch did not show a significant change.