To provide a thermoplastic resin composition having a very high heat conductivity as compared to general-purpose plastics, and simultaneously being excellent extrusionability and blow moldability.

The high-heat conductive thermoplastic resin composition comprises a thermoplastic polyesteric resin, a high-heat conductive inorganic compound having a heat conductivity as a single substance of ≥5 W/mK, and a copolymer obtained by copolymerizing 30 to 100 wt% of methyl methacrylate, 0 to 70 wt% of a (meth)acrylate ester excluding methyl methacrylate, and 0 to 20 wt% of a vinylic monomer copolymerizable therewith, and having a specific viscosity of 0.5 to 7 as measured at 30°C by dissolving 0.4 g of the copolymer is dissolved in 100 cc of toluene.