The stroller applies a first link of the linkage assembly pivotally connecting between the handle and the protecting guard and a second link of the linkage pivotally connecting between the front frame and the protecting guard. During the folding process of the stroller, the first and the second links drive the protecting guard to move and rotate to a position that is substantially parallel with the handle, the front frame, the rear frame, and the bottom frame, bringing the stroller to a smallest size when in the folded position.