This study examined the neural correlates of mental rotation (MR) in preschoolers using functional near-infrared spectroscopy (fNIRS). Forty-eight preschoolers completed a MR task in which they were asked to rotate a test stimulus to match a target stimulus. Results of comparative and General Linear Model (GLM) analyses revealed significant differences between the High Performance (HP) and Low Performance (LP) groups. The two groups differed significantly in oxyhaemoglobin (HbO) change in Brodmann Areas (BAs) 6, 9 and 44. Specifically, significant increase in HbO in BA 44 was observed in both groups, while significant decrease in deoxyhaemoglobin (HbR) in BA 9 was observed only in the HP group and in BA 44 only in the LP group. These results jointly indicated BA 44 as one of the core neural correlates of MR in preschoolers, while BA 6 and BA 9 might also be involved in MR processing under a compensatory mechanism.