To examine the effect of grain size on piezoelectric constant d33, textured CaBi4Ti4O15 (CBT) and Mn-doped CBT ceramics were prepared with a special emphasis on the control of the grain size. The textured ceramics were prepared using the templated grain growth method. First, the mechanism of microstructure development was examined to design the method to control the grain size. It was found that the morphological change in the matrix grains in the presence of platelike template grains was the major origin of microstructure development. This suggested that the grain size in textured ceramics was determined by the template grain size. Then, textured ceramics with various grain sizes were prepared using template powders with various grain sizes. Finally, the effect of grain size on the value of d33 was evaluated. It was found that the grain size had a small effect on the value of d33 for textured CBT and Mn-doped CBT ceramics.