A keyswitch support connection structure incudes a bottom plate portion, a cantilever plate, and a joining portion. The cantilever plate extends upward from a joining hole of the bottom plate portion and has a holding structure. The joining portion and the joining hole are firmly engaged with each other. The joining portion encapsulates the holding structure. The joining portion and the bottom plate portion jointly form or the joining portion alone forms a support connection portion. A keyswitch structure includes a base, a keycap above the base, and first and second keyswitch supports connected to and between the keycap and the base. The base includes the above keyswitch support connection structure. The first keyswitch support is rotatably connected to the support connection portion.