A distribution analyzing device (20) includes: an obtaining unit (21) which obtains measurement data of a field measured, through a sensor sensing area, independently at each of rotation angles and at each of grid coordinate positions of the sensor sensing area; and a calculation unit (22) which calculates a distribution of the field from the measurement data, using an arithmetic expression obtained by deriving a target harmonic function, which indicates the distribution of the field, using a condition that a convolution of the target harmonic function and a shape function, which indicates a shape of a cross section of the finite sensor sensing area along a plane parallel to the measurement plane, is equal to a provisional harmonic function derived by solving the Laplace equation using the measurement data and a size of the sensor sensing area in a direction perpendicular to the measurement plane.