An elastic zip tie is integrally molded from foam rubber, and includes a long strip of strap, a head located at a front end of the strap, and a plurality of flexible grips axially spaced on an upper and a lower surface of the strap. At least one holding space is defined by between any two adjacent axially-spaced flexible grips. The head has a thickness defined between two lateral sides thereof and is substantially larger than a longitudinal length of the holding space, i.e., a distance between two adjacent flexible grips. When a tail end of the strap is extended through the head for the latter to rest on the strap in a selected holding space, the flexible grips located immediately before and behind the holding space are elastically pressed against the two opposite lateral sides of the head to thereby firmly hold the latter in the holding space.