An easily assembled bracket, adapted for being installed at an edge of a bed frame for retaining a mattress on the bed frame includes a fastener and a retainer. The fastener has two wings booth located on an imaginary plane, and a convex protruded from the imaginary plane. A passage is provided between the convex and a top surface of the bed frame. The retainer has an inserting portion detachably inserted in the passage, two stop portions extending from the inserting portion in two adverse directions respectively and abutted against an end of the convex, two extending portions extending from the two stop portions respectively, and at least one retaining portion connected with at least one of the extending portions for being abutted against a side of the mattress.