Stylus includes a first body at the front end and a second body at the back end, where the second body pivots to the first body and is capable of rotating between a straight position and a bending position. The stylus further includes a restraining member selectively moving to engage between the first body and the second body such that the stylus can be retained and formed in a straight pen style with buckling-proof capability, or a bending style for supporting a portable device. When the stylus is drawn out of the portable device, the restraining member can further be pushed forwardly to disengage the second body from the first body by a resilient bump inside the housing of the portable device, so that the stylus can be released from the straight pen style and bended accordingly.