PROBLEM TO BE SOLVED: To measure a relative moving distance of a moving body to a structure easily with high reliability. SOLUTION: This moving distance measuring device for measuring the relative moving distance of the moving body 31 to the conductive structure 2 has an excitation coil 3 for movement detection moving in a body with the moving body 31, on which an alternating voltage is loaded; at least two detection coils 4a, 4b arranged on the front and on the back in the moving direction of the moving body 31 relative to the excitation coil 3 for movement detection, and moving in a body with the moving body 31; and a moving distance operation means for calculating the relative moving distance of the moving body 31 to the structure 2 based on the amplitude ratio and the phase difference between each excitation voltage generated in the detection coils 4a, 4b, and determining the distance between the moving body 31 and the structure 2 based on the amplitude ratio of the excitation voltages to the voltage loaded on the excitation coil 3 for movement detection, to thereby correct the relative moving distance. COPYRIGHT: (C)2007,JPO&INPIT