A dense composite material of the present invention contains 37% to 60% by mass of silicon carbide grains, also contains titanium silicide, titanium silicon carbide, and titanium carbide, each in an amount smaller than the mass percent of the silicon carbide grains, and has an open porosity of 1% or less. Such a dense composite material is, for example, characterized in that it has an average coefficient of linear thermal expansion at 40° C. to 570° C. of 7.2 to 8.2 ppm/K, a thermal conductivity of 75 W/mK or more, and a 4-point bending strength of 200 MPa or more.