A key structure includes a base plate, a triggering element, a keycap and a scissors-type connecting element. The base plate includes an open-type hook and a bulge. The scissors-type connecting element includes a first frame and a second frame. The first frame includes a first base post and an elastic contact part. Due to the structure of the open-type hook, the first frame can be easily assembled with the base plate. Moreover, it is not necessary to retain the gap between the first base posit and the open-type hook. While the first frame is swung, the elastic contact part is pushed by the corresponding bulge. Consequently, the first base post is not detached from the base plate.