Do i need installing antivirus on Windows partition of Mac
Of course, installing an antivirus on your Windows is recommended, but it is not a necessity. Generally, if there was a virus, your mac would not be damaged, as the OS X file format is read only on Windows AFAIK (unless the virus was so well made, that it bypassed this).


  or is all virus protection handled by the Mac?


There is no way for that to happen as when you run Windows with BootCamp, then Mac is not even running, and only mounted as a read-only format on Windows. It is almost like running 2 different systems.