Sanbu District

 is a district located in Chiba Prefecture, Japan. As of January 2013, the district had a population of 49,488 and a population density of 369 persons per km2. The total area is .
Towns and villages.
Elevation of Ōamishirasato to city status.
Ōamishirasato, formerly a town in Sanbu District, was elevated to city status on January 1, 2013, and is no longer part of Sanbu District.
History.
During the early Meiji period establishment of the municipality system on April 1, 1889, the districts of with 3 towns and 14 villages, and with 1 towns and 14 villages were created in what was formerly the north-eastern portion of Kazusa Province. The two districts were formally merged into the new Sanbu District on April 1, 1897.