A sensitivity distribution is estimated for a multicoil used in multicoil fast imaging. Initial sensitivity maps M1 to M3 are produced respectively from images C1 to C3 acquired from the plurality of RF coils in the multicoil. By fitting TPS (thin-plate splines) to the initial sensitivity maps M1 to M3 used as target data, sensitivity maps M1 to M3 for unfolding are estimated. In fitting the TPS, functions are activated, such as automatic arrangement of control points, addition of target points to the outside of an image, use of a known model, and fitting to at least either absolute value components of MR data or phase components of the MR data. Thus, even if only coarse echo data is acquired from the region to be imaged, a sensitivity map of each element coil of the multicoil is estimated with high precision.