Olfactory sensory neurons (OSNs) in the main olfactory epithelium (MOE) detect a large number of odorant molecules with odorant receptors (ORs). In mouse, ~1,200 OR genes have been identified. An individual OSN expresses a single OR gene from this large gene repertoire. OR genes can be classified into two phylogenetically distinct groups, class I and class II. Recently, it has been reported that two types of OSNs are fated to choose either class I or class II OR gene repertoires. However, the mechanism underlying the OR-class choice is not understood. Here we show that the transcription factor Bcl11b/Ctip2 controls the fate-choice of two OSN-types. Bcl11b expression in OSNs is dependent on the class of ORs that they express. Loss of Bcl11b function changed the balance between class I and class II OSNs. This was evident both from OR gene expression and from axonal projection of each class of OSNs. Interestingly, OSN-specific Bcl11b-depletion also disturbed the dichotomy of OSNs as in conventional knockout, suggesting that the fate of OSNs is not completely determined even after terminal differentiation. Moreover, gain of function experiment of Bcl11b gave further information on the machinery for OSN fate-choice mediated by Bcl11b. Thus Bcl11b plays an essential role in the balanced production of class I and class II OSNs.