Semileptonic $B$ decays involving a $\tau$ lepton can be mediated by a charged Higgs boson in New Physics scenarios including an extended Higgs sector, turning these decays into sensitive probes for physics beyond the Standard Model. Indeed, current measurements of the decays $B\to D^{(*)}\tau\nu$ show an excess of the observed branching fractions with respect to the Standard Model expectations. In this article we review two recent experimental studies of semitauonic $B$ decays based on the full data sample of the Belle experiment, a measurement of $B\to D^*\tau\nu$ using the semileptonic tagging method and a search for the decay $B\to\pi\tau\nu$.