Mannequin for the surface treatment of pants. Mannequin for the surface treatment of pants, comprising an upper support structure from which two legs extend, wherein each of said legs has an inflatable balloon arranged at its rear part. Each of said inflatable balloons has its outer lateral section folded upon itself at least once around a folding line extending from the upper edge to the lower edge of the balloon. The upper edge is fixed to the rear upper end of the corresponding leg and the lower edge is fixed to a rear intermediate point of the corresponding leg, such that the parts of the edges corresponding to the outer lateral section are also fixed to the leg of the mannequin.