Abstract: A pivotal connection between hub assembly and ribs of an umbrella, includes a hub assembly having a top face and a bottom face, and multiple slots are defined in the outer periphery, and defined through the top face and the bottom face of the hub assembly. An installation face defined in one of the top face and the bottom face. Each slot has an inclined face defined in two opposite insides thereof, and each inclined face is located to communicate with the installation face. Each slot has a guide extending from each of the two opposite insides thereof. Multiple ribs each have a first end thereof pivotably connected to the slot corresponding thereto via the installation face. The first end of each rib has a first inclined portion to be matched with the inclined face corresponding thereto. The guides restrict the ribs from dropping from the slots.