| Matsuo | |
| Native Name Lang: | ja |
| Settlement Type: | Former municipality |
| Seal Type: | Emblem |
| Pushpin Map: | Japan |
| Pushpin Map Caption: | Location in Japan |
| Coordinates: | 35.633°N 140.467°W |
| Subdivision Type: | Country |
| Subdivision Name: | Japan |
| Subdivision Type1: | Region |
| Subdivision Name1: | Kantō |
| Subdivision Type2: | Prefecture |
| Subdivision Name2: | Chiba Prefecture |
| Subdivision Type3: | District |
| Subdivision Name3: | Sanbu |
| Extinct Title: | Merged |
| Extinct Date: | March 27, 2006 (now part of Sanmu) |
| Leader Title: | Mayor |
| Leader Title1: | Vice Mayor |
| Unit Pref: | Metric |
| Area Total Km2: | 37.59 |
| Population Total: | 11,121 |
| Population As Of: | November 1, 2005 |
| Population Density Km2: | 296 |
| Timezone1: | JST |
| Utc Offset1: | +09:00 |
| Blank Name Sec1: | City hall address |
was a town located in Sanbu District, Chiba Prefecture, Japan.
Matsuo Village was formed on April 1, 1889 within Musha District. Musha District became part of Sanbu District from April 1, 1897. On August 31, 1898, Matsuo was raised to town status. It expanded through the annexation of the neighboring villages of Ohira and Toyooka on February 1, 1955.
On March 27, 2006, Matsuo, along with the towns of Narutō and Sanbu, and the village of Hasunuma (all from Sanbu District), was merged to create the city of Sanmu,[1] and thus no longer exists as an independent municipality.
As of November 1, 2005, (the last census data prior to the merger) the town had an estimated population of 11,121 and a population density of 296 persons per km2. The total area was 37.59 km2.