A review is given on heat flow measurement and its interpretation techniques for marine methane hydrate exploration. In addition to seismic reflection data (BSRs), or instead of BSR data, heat flow measurement could provide useful means to estimate the distribution of subbottom methane hydrates, if we resolve some technical problems, such as a success in careful long-term measurement using a sea-floor heat flow probe. Solving those problems will lead to our better knowledge of the heat transfer mechanisms, and then contribute to answering some fundamental questions on marine methane hydrates that have been raised by the recent results of the ocean drilling program. Also, implications of the heat flow data obtained for methane hydrates to the problem of oceanic plate subduction processes are briefly mentioned.