A near-field terahertz wave detector comprises a semiconductor chip (12) whose longitudinal electrical resistance along its surface changes due to a near-field wave of a terahertz wave (1), an insulating film (18) which covers the surface of the semiconductor chip, and a conductive film (20) able to shield the terahertz wave by covering the surface of the insulating film. The conductive film (20) has an aperture (21) whose maximum size is one digit or more smaller than the wavelength of the terahertz wave. Further, a planar conductive probe (14) is provided between the conductive film (20) and the semiconductor chip (12). The conductive probe (14) is insulated from the conductive film (20) by the insulating film (18), and a tip (14a) of the conductive probe (14) is located inside the aperture (21). It is possible to increase a signal-to-noise ratio by significantly reducing the effect of a far-field wave, thereby enabling a near-field wave to be detected with high efficiency and increasing the resolution of an object by the near-field wave to one tenth or less of the wavelength.