Searches for ttH production at CMS

Results of searches for the Higgs boson production in association with a pair of top quarks using the proton-proton collision data collected by the CMS detector at LHC are presented. First, results of the searches at centre-of-mass energy of 13 TeV are briefly discussed. Then, the combination of results at centre-of-mass energies of 7, 8, and 13 TeV are presented, which provides an observation of the Higgs boson production in association with a pair of top quarks with a significance of 5.2 standard deviations.