A former magistrate and former Minister of Justice, Mr. Belaiz, 70, has already chaired the Constitutional Council from March 2012 to September 2013.
At the time, the calls had multiplied, in vain, so that the Council initiates a procedure of prevention of Mr. Bouteflika, victim in 2013 of a stroke and hospitalized in France for 80 days.
Mr Belaiz had left the Council after being appointed Minister of the Interior, and in 2015, special advisor to Mr Bouteflika.
He replaces Mourad Medelci, who died in January from an illness at the age of 76.
Composed of 12 members, the Constitutional Council is responsible for validating the candidatures to the presidential election, to control the regularity of the poll and to proclaim the final results.
It is also responsible for launching the procedure for finding the impeachment of the Head of State for "serious and lasting illness" and to note the definitive vacancy of the presidency, in case of death or resignation of the latter.
Four members of the Council, including the President and Vice-President, are appointed by the Head of State, two are elected by each of the two Houses of Parliament, two by the Supreme Court and two by the Council of State.
Candidates for the presidential election of April 18 have until March 3 at midnight (23:00 GMT) to file their case with the Constitutional Council.
Aged 81, Mr Bouteflika, in power since 1999, announced Sunday his candidacy for a 5th term.