Abstract: An inspection apparatus 20 is for an inspection of a target region 13 including a part of a subsurface portion 12 of a sample 10 having an approximately circular cross section. The inspection apparatus 20 includes an X-ray source 40 that emits X-rays, a crystal plate 70 being a single crystal, and a detector 80. The crystal plate 70 is disposed to reflect and diffract X-rays (refractive X-rays X5) having been emitted by the X-ray source 40 and refracted in the target region 13. The crystal plate 70 is disposed to allow X-rays (rectilinear X-rays X3) having been emitted by the X-ray source 40 and entering the crystal plate 70 without having been incident on the sample 10 to transmit through the crystal plate 70. The detector 80 detects an intensity of the X-rays (reflected and diffracted X-rays X7) reflected and diffracted by the crystal plate 70.