A stylus suitable for an electronic device is provided. The stylus comprises a pen barrel and a core. The pen barrel has a sidewall and at least one first protrusion, and the first protrusion is located at an inner side of the sidewall. The core movably passes through the pen barrel. The core has a pen tip and at least one second protrusion. Under a first status, the first protrusion and the second protrusion are dislocated from each other. Under a second status, the first protrusion and the second protrusion are aligned with each other to make a part of pen barrel expand and deform.