The was a private railway in Chiba Prefecture, Japan. It connects Narashino and Matsudo. It was a subsidiary of Keisei Electric Railway.
It also operated the following bus company subsidiaries.
The company operated one line, the Shin-Keisei Line, between Matsudo and Keisei Tsudanuma.
All trains were based at Kunugiyama and Tsudanuma Depots.
After World War II, the ownership of the right-of-way of an uncompleted Imperial Japanese Army military railway line was transferred to Keisei. Shin-Keisei was established as a subsidiary of Keisei on 23 October 1946 to construct and operate the line. The first section of the line, from to , was opened on 27 December 1947, with a track gauge of and electrified at 1,500 V DC overhead. The line was regauged to in October 1953, and the entire line was completed as a single-track line by 21 April 1955. In August 1959, the line was again regauged, this time to to match the standard gauge used by Keisei Electric Railway.
In June 2014, the company unveiled a new corporate image with a new corporate logo and "gentle pink" corporate colour scheme and train livery. The company's entire fleet of trains was scheduled to be reliveried in the new colour scheme, with the first train, an 8800 series set entering service from 29 August 2014.
In an announcement made on 31 October 2023, Shin-Keisei Electric Railway revealed that it would be merged into the parent Keisei Electric Railway. The acquisition was completed on 1 April 2025, and the line was renamed as the Keisei Matsudo Line. The merger also resulted in the bus company subsidiaries being acquired by parent company, Keisei Electric Railway.