Depressurization is considered a promising technique of producing gas from methane hydrate reservoirs. This report presents a dissociation model and an experimental study of core on gas production to clarify the dissociation characteristics during depressurization. The dissociation model can be expressed as a function of heat transfer and mass transfer. In our experiments, we used an artificial sedimentary core and performed several depressurization experiments under various production pressure conditions. The temperature, pressure, and production volumes of gas and water were measured in response to time. By comparing the developed dissociation model with our core experimental results, it is clearly demonstrated that the model can describe the experimental results well and that the heat transfer from the surroundings is predominant in our experimental case. In addition, we conclude that our developed model can predict the quantitative characteristics during the gas production process from core.