An objective is to enable calculation of a distribution of a physical property such as a density inside a measurement object, even when the distribution of the physical property value is non-uniform, within a feasible period of time without causing image deterioration due to phenomena such as refraction and multiple-reflections caused by the non-uniformity. To this end, the physical property value that makes an evaluation quantity be an extremum is outputted, where the evaluation quantity is a liner sum or a product of exponential function of: an equation residual quantity that is a residual being a difference between an operator term and an external force term of an equation of motion; a non-uniformity detection equation residual quantity that is a residual of an equation of detecting the non-uniformity of the physical property value from a matching degree of solutions of the equation of motion under two types of boundary conditions; and a conditional equation residual quantity that is a residual of a constraint condition.