Microstructural evolution during intercritical annealing after rapid heating of cold rolled low carbon steels was investigated by EBSD and TEM. When the specimens were heated to above the Ac₁ temperature before the completion of the primary recrystallization of α and then annealed, remarkable retardation of the primary recrystallization was observed, resulting in non-uniform grain size distribution of α. Because of the retardation, subgrains formed in non-recrystallized α are not consumed by recrystallized α and are thus able to gradually grow with annealing, and finally the grain size distribution of α becomes uniform. The analysis based on the rⁿ−r_0ⁿ=kt equation has shown that the subgrain growth in non-recrystallized α from the holding period of 100 to 1000 s follows n=3, indicating that the subgrain growth is controlled by the volume diffusion of Mn at α and γ interfaces. The transition of n from 3 to 2, observed at the holding time of longer than 1000 s, may be due to the gradual disappearance of the smaller γ phase at subgrain boundaries.