To provide a composite thermal insulation material that uses a resin foam as a substrate, is small in thickness and weight and has excellent resistance to combustion performance.

The composite thermal insulation material is formed by laminating a resin foam and a mortal composition containing cement, an inorganic filler and a fiber. The mortar composition contains 110-1,000 pts.mass of the inorganic filler and 0.5-30 pts.mass of the fiber based on 100 pts.mass of the cement, and 100-800 pts.mass of an endothermic material and 10-200 pts.mass of an inorganic lightweight aggregate are contained in the inorganic filler. The resin foam and the mortar composition are preferably laminated via a coating film of an undercoating material containing a resin binding material, an endothermic material and a scaly inorganic particle.