The measure will be part of legislation to be tabled this fall that is aimed at toughening Bill 101, Nicole Leger told The Canadian Press.
''Bill 101 is going to be changed,'' Leger said.
''I will have plenty of support as family minister to make sure it also extends to daycares.''
Quebec has various types of child-care centres and it is not immediately clear whether the new legislation will apply to all of them.
Premier Pauline Marois has made it clear she intends to strengthen the French Language Charter, which actually falls under the purview of another cabinet minister, Diane De Courcy.
Another possible measure would force companies with between 11 and 50 employees to make French the official language of the workplace. Currently, that provision applies only to those with 50 or more workers.
The PQ has said it will take special aim at Montreal and the Outaouais region in western Quebec where the party believes French is under particular threat.
Bill 101 was passed by the PQ government in 1977 and makes it compulsory for the children of most immigrants to attend French-language schools.
The PQ has also made noise about extending Bill 101 to post-secondary junior colleges.
The law also imposes restrictions on the use of languages other than French on commercial signs.
Leger said in the same interview she wants to create 32,000 new daycare spaces, at $7 a day, to reach a total of 250,000 by 2016.