Current research on methane hydrate as an energy resource makes a remarkable advance under the national research projects in Japan, Canada, and US and several field production tests were carried out for demonstrating methane hydrate gas production. The methanol huff-and-puff stimulation was proposed as a possible way for improving gas productivity of such a methane hydrate well. Numerical studies are presented to demonstrate that the huff-and-puff stimulation before depressurization works well in improving gas productivity. The methanol huff-and-puff stimulation consists of the two-process cycles, i.e., injection of a methanol-solution slug into the well, and flowback with depressurization. Based on calculation using our numerical simulator, MH2I-HYDRES (MH2I Hydrate Reservoir Simulator), hydrate dissociation behavior during the huff-and-puff stimulation and successive gas production performance was evaluated for a hypothetical methane hydrate well. Huff-and-puff stimulation dissociated hydrates near the wellbore for the formation to produce gas at much higher rates than the ones without stimulation. Formation temperature went down below zero along the hydrate equilibrium curve during the huff-and-puff cycles and the decreased temperature helped the surrounding formation to supply heat for promoting hydrate dissociation. In some cases, hydrate regenerated in the region where hydrate-dissociated water dilutes methanol, but its influence was little. Huff-and-puff schedule like huff/puff time ratio and methanol-slug concentration affected the stimulation results. This is an abstract of a paper presented at the Offshore Technology Conference - Waves of Change (Houston, TX 5/5-8/2008).