During the demonstrations held in Nashik city, Nandgaon, Yeola and other places, slogans were raised hailing Bhujbal, a prominent OBC leader.
Bhujbal was arrested in March 2016 in Mumbai by the Enforcement Directorate (ED) in connection with its probe in a money laundering case registered against him and others.
The NCP had alleged that Bhujbal's arrest was an act of "political vendetta" by the ruling BJP, which has rejected the charge.
In December last year, a special court in Mumbai had rejected Bhujbal's bail plea.
More From This Section
"Bhujbal was put in jail by the state government out of political vendetta and revenge," said Nashik district NCP president Ravindra Pagar.
Nashik is the home district of Bhujbal.
Wearing black clothes, around 100 activists of NCP and Samta Parishad staged a protest in central Nashik.
A memorandum was later submitted to the district collector.
Local NCP leaders including former MP Devidas Pingale, city unit president Ranjan Thakareand others participated in the protest.
Alleging that the government was purposefully opposing Bhujbal's release from jail, the NCP leaders referred to the striking down of Section 45 (1) of the Prevention of Money Laundering Act (PMLA) by the Supreme Court in November last year.