Mansalay, officially the Municipality of Mansalay (Tagalog: Bayan ng Mansalay), is a municipality in the province of Oriental Mindoro, Philippines. According to the 2020 census, it has a population of 59,114 people.

This town is notable for its indigenous Mangyan population. The municipal hall is located on the upper land of Mansalay Town proper, in front of a Medical Care Hospital. Nearby is the church and the only Catholic School, Mansalay Catholic High School. Santa Catalina is the town's patron saint.

The town also has a wide ammonite formation area discovered in the 1940s. Since then, thousands of ammonite fossils have been discovered. Due to the complexity and vastness of the collection found in the area, the town has been called the Ammonite Capital of the Philippines. Various local and international scientific institutions have conducted research on the ammonite formations of Mansalay. Scholars have argued that due to the natural significance of the area to Southeast Asian pre-history, the site has a big chance of being declared as a UNESCO World Heritage Site or a UNESCO Geopark Reserve. It is 144 kilometres (89 mi) from Calapan.

The etymology of Mansalay is thought of to have originated from a conversation between the indigenous datu of Mansalay at the time, Abucay, and Spanish conquistadores. When Spanish conquistadors arrived at present-day Mansalay, they inquired the datu of Mansalay, Abucay, about the name of the area. To which, Datu Abucay responded with the phrase: "Man may malay" in the indigenous language which meant "I don't know." Indicating the failure of Datu Abucay to understand the inquiry of the Spanish conquistadors. Subsequently, they (Spanish conquistadors) thought that Abucay gave the real name of the area in spite of the clear language barrier. Henceforth, Spanish conquistadors recorded the area's name as Mansalay.

Prior to the Spanish arrival, and eventual colonisation in the Philippines, Mansalay was inhabited by migrants from nearby islands in the Philippine archipelago such as Palawan and Panay.

During the Spanish colonisation of the Philippines, Mansalay was under the jurisdiction of the government of Mangarin, Mindoro. (present-day San Jose, Occidental Mindoro.)

In the year of 1901, during the Philippine-American War, Mansalay was occupied by American forces.

On the 24th of July, 1929, Mansalay was made its own municipality by a bill authored by Mariano Leuterio, representative at the time for Mindoro. Teotimo P. Cusi became the first Municipal-President.

During the later-Interwar years, Mansalay attracted migrants from provinces in Central Luzon, Batangas, Romblon, and Capiz.

In the 16th of December 1944, Mansalay was liberated by American troops from the Japanese occupation forces in the Battle of Mindoro

Mansalay is politically subdivided into 17 barangays. Each barangay consists of puroks and some have sitios.

In 1957, the sitios of Santa Brigida, Santa Maria, Roma, Budburan, and Mahabangsapa were constituted into barrios.

Population census of Mansalay

Year	Pop.	±% p.a.
1939	7,003	—
1948	11,223	+5.38%
1960	14,669	+2.26%
1970	18,395	+2.29%
1975	19,544	+1.22%
1980	23,548	+3.80%
1990	27,515	+1.57%
1995	29,765	+1.48%
2000	39,041	+5.99%
2007	43,974	+1.65%
2010	51,705	+6.07%
2015	54,533	+1.02%
2020	59,114	+1.60%
Source: Philippine Statistics Authority

Poverty incidence of Mansalay

10 20 30 40 50 60 2006 54.50 2009 41.82 2012 35.54 2015 31.82 2018 23.30 2021 33.45 Source: Philippine Statistics Authority

Its people relies heavily on fishing and farming to survive and earn a living. Because of meager income opportunities, Mansalay has produced a large number of overseas Filipino workers who send remittance back.

• Mansalay Profile at PhilAtlas.com
• Philippine Standard Geographic Code
• Philippine Census Information
• Local Governance Performance Management System
• Mansalay Official Home Page