Belmar is a borough in Monmouth County, New Jersey, United States. As of the 2010 United States Census, the borough's population was 5,794, reflecting a decline of 251 from the 6,045 counted in the 2000 Census, which had in turn increased by 168 from the 5,877 counted in the 1990 Census.What is now Belmar was originally incorporated as Ocean Beach borough by an act of the New Jersey Legislature on April 9, 1885, from portions of Wall Township, based on the results of a referendum held two days earlier. On April 16, 1889, it became the City of Elcho borough, which lasted for a few weeks until the name was changed to the City of Belmar Borough as of May 14, 1889. The city acquired its current name, Borough of Belmar, on November 20, 1890. The borough's name means "beautiful sea" in Italian.