The company has advertised for offers for the 929 perch block with 169,000 square feet of factory and office space.
"We're selling the property because we're moving to a new site in Dankotuwa where we have set up a new plant," a company official said.
Manufacturing has already started at the new plant in Dankotuwa with full production expected from April 1.
The site on sale is within the Welisara industrial complex with a convenient location being 100 metres from the existing main road and four km from the planned new highway between Colombo and the airport.
Company officials said it was also useful for export industries being 16 km from Colombo port and 13 km from the Katunayake international airport.
Existing facilities at the Welisara site include a sewerage treatment plant and parking space.
"All our consumer goods were made there, such as soaps and toothpaste," said a company official.
"All the buildings are ready to use and made for installation of heavy machinery. For example, the buildings can easily be converted for garment manufacturing."
Hemas employed about 500 people at the Welisara complex but company officials said it could accommodate even more as Hemas production was partly automated and did not need a lot of staff..