Effective thermal conductivity (ETC) of both tetrahydrofuran (THF) and methane hydrate-bearing sandy porous media was measured by the Hot Disk Thermal Constant Analyser. Thermal conductivity of methane hydrate is 0.575 W m-1 K-1 at 0¿C and 6.6 MPa (methane gas pressure), which is close to THF hydrate's 0.51 W m-1 K-1 at 0¿C and 0.1 MPa (atmosphere pressure). However, the measured 1 W m-1 K-1 ETC of methane hydrate-bearing sand is significantly lower than that of THF hydrate-bearing sand at ~2 W m-1 K-1. This is because the methane hydrate formed with a sodium dodecyl sulfate (SDS) solution in sand at our laboratory has a wall creeping growth characteristic and consequently a large part of the pores were filled with methane free gas. ETCs of sand containing gas hydrates were also calculated using a renormalization method. The process involves sample partitioning, labeling, initial value assignments, and renormalization calculations. A Monte Carlo analysis was applied to sample laboratory-scale gas hydrate-bearing sand assemblies. We found that the renormalization modeling results agreed well with measured ETCs when each photo of a 1.3 mm ¿ 1.3 mm subsample was divided into 16 or more blocks.