Abstract: An improved key structure, for keyboards, comprises a keycap and a scissor-like assembly disposed above a bottom plate. A membrane sheet containing an electrical circuit is placed on the bottom plate and is provided with a silicone elastomer at a center thereof. A middle plastic plate has first engagement portions and second engagement portions and is placed on the membrane sheet. The scissor-like assembly has engagement members and is pivotally mounted to the first engagement portions and the second engagement portions of the middle plastic plate. The keycap is mounted on the scissor-like assembly. The engagement portions of the middle plastic plate and the engagement members of the scissor-like assembly are configured symmetrically, so that the scissor-like assembly can be pivotally mounted to the middle plastic plate in a direction, being horizontally reversed to its original direction, so as to simplify the operation of assembling parts of the key structure.