Аннотация:A search is performed for the lepton number violating decay B+→h−μ+μ+B+→h−μ+μ+, where h−h− represents a K−K− or a π−π−, using data from the LHCb detector corresponding to an integrated luminosity of 36pb−136pb−1. The decay is forbidden in the Standard Model but allowed in models with a Majorana neutrino. No signal is observed in either channel and limits of B(B+→K−μ+μ+)<5.4×10−8B(B+→K−μ+μ+)<5.4×10−8 and B(B+→π−μ+μ+)<5.8×10−8B(B+→π−μ+μ+)<5.8×10−8 are set at the 95% confidence level. These improve the previous best limits by factors of 40 and 30, respectively.