1. A magnetic resonance imaging device comprising a static magnetic field applying part for applying a static magnetic field to a subject, a gradient magnetic field applying part for applying a gradient magnetic field to the subject, a high frequency magnetic field pulse irradiating part for irradiating the subject with a high frequency magnetic field pulse, a receiving part for receiving a nuclear magnetic resonance signal from the subject, and a computing part for calculating the nuclear magnetic resonance signal received by controlling the gradient magnetic field and the high frequency magnetic field pulse, wherein the computing part includes a measurement unit for detecting the nuclear magnetic resonance signal generated from the subject as a complex signal by applying the high frequency magnetic field pulse and the gradient magnetic field to the subject placed in the static magnetic field, an image reconstruction unit for reconstructing a complex image in which each pixel value is a complex image, from the complex signal, an image conversion unit for converting the complex image into a magnetic susceptibility image, and a display processing unit for displaying the created image on a display; the image conversion unit includes a complex image conversion unit for creating an absolute value image and a phase image from the complex image, and a magnetic susceptibility image calculation unit for creating the magnetic susceptibility image from the phase image, and the magnetic susceptibility image calculation unit includes an edge information magnetic susceptibility image calculation unit for calculating an edge information magnetic susceptibility image indicating an edge of a tissue in a magnetic susceptibility distribution, and an edge mask calculation unit for calculating an edge mask of a tissue from the edge information magnetic susceptibility image.