The invention relates to an automatic tool setting device, which comprises a base, a tool setting shaft partially held in the base, and a first elastic element held in the base and elastically pressing against the tool setting shaft. The base comprises a holding part and a holding hole communicating with the holding part; and the holding part is provided with a bottom surface opposite to the tool setting shaft. Part of the tool setting shaft is held in the holding part; the tool setting shaft is clamped and held on the base; and two ends of the first elastic element press against the bottom surfaces of the tool setting shaft and the holding part. The automatic tool setting device further comprises a sensor held in the holding hole; and the sensor is used for sensing displacement information of the tool setting shaft. The automatic tool setting device provided by the invention has higher tool setting accuracy.