Abstract: A robot includes a base, a pivot base, an upper arm, and a lower arm. The base is fixed to an installation surface. The pivot base has a pivot base proximal end which is connected to the base such that the pivot base is rotatable around a first axis along a vertical direction. The lower arm includes a first extending portion, a second extending portion, and a connecting portion. The connecting portion has a hollow structure and connects the first extending portion and the second extending portion such that the first arm proximal end faces the second arm proximal end and such that the first arm distal end faces the second arm distal end. The connecting portion includes a reinforcing portion in the hollow structure. The reinforcing portion includes ribs which connect opposed inner walls of the connecting portion and which cross each other.