Tsirpas, 40 years old and the youngest head of Greek Government in a century and a half, swore to observe the Constitution and laws of the country and to safeguard the interests of the people, in a ceremony at the Presidential Palace and before the President Papoulias Karalos, Prensa Latina News Agency reports said.
SYRIZA, formed by 13 organizations and created as a partnership in 2012, won yesterday's 36.34 percent of the votes in the general election, to meet with 149 of the 300 seats in the unicameral parliament Greek.
The leftist party agreed this day to form a government with the nationalist Independent Greeks, which obtained 13 seats after the election.
Tsirpas followers advocated a program to repeal the austerity measures implemented by the Conservatives in the Greek cabinet that worsened the economic situation of the country.