There is provided a hair fastener. The hair fastener has an elongate body made of an elastic material stretchable under tension for maximizing holding capability of hair and a locking means at least part of which made of a stiff material. The locking means includes a first member and a second member arranged at opposite ends of the body. The first member and the second member are releasably engageable with each other by way of a mechanical interference fit in that engagement of the first and second members is achieved independent of degree of tension of the elastic body and engagement or disengagement of the first and second members is achieved by way of one hand operation of a user. The fastener is adapted to assume a first configuration in which the first member and second members are engaged before tying the hair and a second configuration in which the first and second members are disengaged whereby removal of the fastener from the hair in the second configuration minimizes movement of the fastener along the length of the hair and thus eliminating or at least reducing frictional contact with the hair. With this construction, majority part of the hair fastener can be made of a high friction material to provide improved gripping or holding security of hair and yet hair is not damage during removal of the fastener from user's hair.