In a sheet material (1), a bonding layer (2) is provided, and then a high-strength layer (3) is laminated on the bonding layer (2). The bonding layer (2) is made of an epoxy resin being a thermosetting material. The high-strength layer (3) is made of polyimide, which is not softened at a thermosetting temperature of the epoxy resin and has a tensile rupture strength higher than that of the cured thermosetting material. Moreover, the polyimide has a tensile rupture strength of 100 MPa or higher at 23° C. and a tensile rupture elongation of 10% or higher at 23° C. Assuming that a tensile rupture strength at −65° C. is a and a tensile rupture strength at 150° C. is b, a ratio (a/b) is 2.5 or less.