Although bainite transformation in steels is strongly affected by the initial microstructurc, the effect of the secondary phase existing before bainite transformation is not yet well understood. In the previous study, we investigated the effect of pre-existing marlcnsitc on the kinetics of bainite transformation and confirmed that the crystallographic orientations of bainitic ferrite laths were affected by neighboring martcnsitc. The aim of this work is to clarify the effect of pre-existing martcnsitc on the block size and crystallographic features of bainite. Lath-shaped bainite structures grown from mixed initial structures of austenite and martcnsitc were investigated in Fc-0.2C-8Ni alloy transformed at various temperatures. At high temperatures, 723 K and 693 K, pre-existing marlcnsitc makes a huge bainite block around itself and coarsens other fine blocks. This coarscning of bainite block size results from the variant selection rule added to bainitic ferrite laths by pre-existing martcnsitc. On the other hand, at low temperatures, 643 K, these effects of pre-existing martcnsitc on bainite block size are inconspicuous. This weakening of the cffcct of martcnsitc with the decrease in transformation temperature is understandable with the increase in driving force of bainitic ferrite nucleation.