Among those putting in their papers were Deputy Chief Minister Ajit Pawar, Public Works Minister Chhagan Bhujbal, Home Minister RR Patil and Rural Development Minister Jayant Patil.
Sources said that the move should be seen in the light of NCP chief Sharad Pawar's recent directions to party leaders asking them to prepare for next year's Lok Sabha elections.
The NCP ministers submitted their resignations to Pawar at a meeting of senior party leaders at the residence of the deputy chief minister here this evening, sources added.
NCP shares power with Congress in the state government.
There were reports that Maharashtra NCP chief Madhukar Pichad and party leader and Assembly Speaker Dilip Walse Patil, too, have submitted their resignations.
The new president of the NCP state unit may be announced in around a week's time, sources said.