A dive knife with two elastic buckles at two lateral sides includes a handle having a long groove therein; a buckle; each of a right side and a left side of the buckle having an upward elastic key; each elastic key extending upwards and being biforked at an upper end thereof so as to form with two claws; one claw near the body being as a hooking claw and another claw far away from the body being as a press key; a knife; a retaining set installed to the inner side of the rear cover; a front end of each left and right side of the lower retainer is extended with an elastic hook; and wherein in assembly, the buckle is received into the groove of the handle, the elastic hook will hook with the hooking claw of the elastic key of the buckle.