PROBLEM TO BE SOLVED: To provide a moving object visualization method and visualization device capable of visualizing even an object having a low frequency of appearance, such as the quantization of a bubble distribution of boiling two-phase flow.SOLUTION: In a visualization method for arranging a radiation source 11 and a radiation detector 12 around a measuring object 1 with a moving object moving thereinside, rotating the radiation source and the radiation detector around the measuring object to photograph a transmission image from all directions of the measuring object by relatively moving either the radiation source and the radiation detector or the measuring object with respect to the other, and reorganizing the transmission image from all directions to acquire a cross-sectional image, a plurality of the transmission images of the measuring object from all directions by rotating the radiation source and the radiation detector around the measuring object a plurality of times, transmission images from all directions obtained by overlappingly adding the plurality of transmission images from all directions in each direction are acquired, and the added transmission images from all directions are reorganized to acquire a cross-sectional image.