ジェフユナイテッド市原・千葉
, full name JEF United Ichihara Chiba and also known as , is a Japanese professional football club that plays in the J2 League. On 1 February 2005, the club changed its name from "JEF United Ichihara" to the current name after Chiba city had joined Ichihara, Chiba as its hometown in 2003. Of its club name, "JEF" is taken from the JR East and Furukawa Electric companies and "United" is meant to represent the unity of the club and its home city.