We consider the extension of the Standard Model with an extra scalar S which decays can be responsible for the diphoton excess with invariant mass ~ 750 GeV observed at the 13 TeV LHC run. Two scenarios of S production are considered: gluon fusion through a loop of heavy isosinglet quark(s) and photon fusion through a loop of heavy isosinglet leptons. In the second case many heavy leptons are needed or/and they should have large electric charges in order to reproduce experimental data on σpp→sx·Br(S → γγ)