We have studied field trapping ability of single grain Gd–Ba–Cu–O bulk superconductor 140mm in diameter, which was fabricated by using Gd 2 BaO 4 and Ba–Cu–O phase as raw materials. The distribution of the trapped magnetic field showed single domain without serious weak links, when the bulk was field-cooled in 1T at liquid nitrogen temperature. The maximum trapped magnetic field at 77K and 65K were 2.30T and 3.66T respectively, when a field of 4T was applied. From the distribution measurements of magnetic field, it was confirmed that a large amount of flux can be trapped in this large bulk. It was also confirmed that magnetic field can reach a longer distance in a larger bulk than smaller diameter samples.