According to the present invention, the CT is carried out based on parameters other than the absorption rate. An electromagnetic wave measurement device includes an electromagnetic wave output device 2 which outputs an electromagnetic wave at a frequency equal to or more than 0.01 [THz] and equal to or less than 100 [THz] toward a device under test 1, an electromagnetic wave detector 4 which detects the electromagnetic wave which has transmitted through the device under test 1, a relative position changing unit 6 which changes a relative position of an intersection 100 at which an optical path of the electromagnetic wave transmitting through the device under test 1 and the device under test 1 intersect with respect to the device under test 1, a phase deriving unit 12 which derives, based on a detected result by the electromagnetic wave detector 4, a phase in the frequency domain of the electromagnetic wave which has transmitted through the device under test 1, a sinogram deriving unit 16 which derives a sinogram based on a derived result by the phase deriving unit 12, and a cross sectional image deriving unit 18 that derives, based on the sinogram, an image of a cross section of the device under test 1 including a trajectory of the intersection 100.