Beyond Standard Model searches in B decays with ATLAS

The proceeding contribution presents recent results of the ATLAS experiment at the LHC on heavy flavour measurements sensitive to possible contributions of the new physics. Two measurements are overviewed: the angular analysis of $B^0\to\mu^+\mu^- K^{*0}$ decay and measurement of relative width difference of the $B^0$-$\bar{B}^0$ system. The first one uses a data sample with an integrated luminosity of 20.3 fb$^{-1}$ collected by ATLAS at a centre of mass energy $\sqrt{s} = 8$ TeV, and the second one benefits from the full ATLAS Run-1 dataset with additional 4.9 fb$^{-1}$ collected at $\sqrt{s} = 7$ TeV.