A handle extension structure includes a connection assembly and an operation assembly. The connection assembly has a first end and a second end opposite to each other. The operation assembly is slidably disposed at the connection assembly. The operation assembly includes an extension element and a grip element. The extension element has a first end portion and a second end portion opposite to each other. The first end portion is slidably disposed between the first end and the second end. The grip element is pivoted to the second end portion. An electronic device casing includes a body, a movable apparatus, and the handle extension structure. The handle extension structure is pivoted to the movable apparatus through the connection assembly.