A button , applied to an electronic device and comprising at least: an inner button and an outer button , wherein at least a part of an end of the inner button close to the outer button is built into the outer button; the outer button comprises a pressing surface and a back surface opposite to the pressing surface, and the inner button is disposed on the back surface of the outer button ; the inner button comprises at least a function part , and a size (L3) of the outer button in a width direction of the button is the same as a size (L4) of at least a part of the function part in the width direction of the button; and one outer side wall of the outer button in a length direction of the button is flush to one outer side wall of the function part in the length direction of the button, and the other outer side wall of the outer button in the length direction of the button is flush to the other outer side wall of the function part in the length direction of the button; wherein the inner button further comprises a first connection part ; and one end of the first connection part is connected to the function part , and the other end of the first connection part is connected to a middle frame of the electronic device ; wherein the inner button further comprises a second connection part , one end of the second connection part is connected to the function part , and the other end of the second connection part is connected to the first connection part ; wherein at least one gap is disposed on at least one outer side wall of an end of the second connection part close to the function part in the length direction of the button, so that at least a part of the back surface at a location at which the outer button is opposite to the first connection part is exposed. an inner button and an outer button , wherein at least a part of an end of the inner button close to the outer button is built into the outer button; the outer button comprises a pressing surface and a back surface opposite to the pressing surface, and the inner button is disposed on the back surface of the outer button ; the inner button comprises at least a function part , and a size (L3) of the outer button in a width direction of the button is the same as a size (L4) of at least a part of the function part in the width direction of the button; and one outer side wall of the outer button in a length direction of the button is flush to one outer side wall of the function part in the length direction of the button, and the other outer side wall of the outer button in the length direction of the button is flush to the other outer side wall of the function part in the length direction of the button; wherein the inner button further comprises a first connection part ; and one end of the first connection part is connected to the function part , and the other end of the first connection part is connected to a middle frame of the electronic device ; wherein the inner button further comprises a second connection part , one end of the second connection part is connected to the function part , and the other end of the second connection part is connected to the first connection part ; wherein at least one gap is disposed on at least one outer side wall of an end of the second connection part close to the function part in the length direction of the button, so that at least a part of the back surface at a location at which the outer button is opposite to the first connection part is exposed. <EOS>