— As jumping is an effective method of moving over rough terrain, there is much interest in building robots that can jump, and deformation of a soft robot’s body is an effective method to induce jumping. Our aim was to investigate the effect of the initial shape of deformation of a circular shell made of spring metal. Four initial shapes of deformation, dish, peanut, cup and cap, jumped the highest in that order, with the dish jumping twice as high as the cap. A simulation of a model was in good agreement with the observations.