The ministry added that six patients who had been infected by the SARS-like virus have been cured.
The new deaths occurred on Monday, with one patient dying in Riyadh and the remaining four in the commercial capital Jeddah.
MERS causes fever, coughing and shortness of breath, and can be lethal particularly among older people and those existing health problems.
Some 30 percent of the several hundred people infected with it have died, according to the US Centers for Disease Control and Prevention.
The virus first emerged in Saudi Arabia in 2012 and recent research has suggested it may originate in camels.
The vast majority of cases have been in Saudi Arabia, but MERS has also been found in 16 other countries.
Most cases involved people who had travelled to Saudi Arabia.