You can visit Italy without a visa if you are:
A national of one of the Schengen countries
A citizen of an EU (European Union) or EEA (European Economic Area) member country, as well as a Swiss national
A national of a non-EU/EEA/Schengen country who is not required to obtain a Schengen visa.
a holder of a Schengen visa/residence permit from another Schengen nation
If not, you will very certainly need to apply for a visa.