A stepping exercise machine includes a base and a pedal. The base is provided with an undulating slide rail. A top end of the slide rail is defined as a peak. Bottom ends of two sides of the peak are defined as troughs. The two sides of the peak or the bottom ends of the troughs are provided with stop blocks, respectively. An underside of the pedal is pivotally connected with rollers. Two sides of the underside of the pedal are fixedly connected with a pair of stretchable elastic members. The other ends of the pair of stretchable elastic members are fixed to two sides of the base. The rollers support and drive the pedal to reciprocate along the undulating slide rail ups and downs by means of the stretchable elastic members.