Provided is an ablation system that is able to improve convenience. The ablation system 5 includes: an electrode needle 1 to be percutaneously punctured into an affected site 90 in a body； and a power supply device including a power supply 32 that supplies, between the electrode needle 1 and a counter electrode plate 4, electric power Pout directed to performing of an ablation, and a controller 33 that controls a supplying operation of the electric power Pout in the power supply 32. The controller 33 measures an impedance value Z between the electrode needle 1 and the counter electrode plate 4 upon the ablation and counts the number of times of break states (the number of times of breaks Nb) in which the impedance value Z has exceeded a threshold Zth (a first threshold), and automatically ends the ablation by automatically stopping supplying of the electric power Pout, in a case where the number of times of breaks Nb has reached a threshold Nth (a second threshold).
