MNS state unit general secretary Vasant Gite was detained as a preventive measure ahead of the possible arrest of party chief Raj Thackeray.
Three leaders of Maharashtra Navnirman Sena (MNS) have also been taken into preventive custody, Police Commissioner S M Sayyad said.
With this, the total number of arrests have gone up to 126 since Tuesday, he said.
Former Shiv Sena leader Vasant Gite was one of the first to join MNS when Raj Thackeray left the Sena and formed his outfit.