A state detection system for a milling tool used includes: a milling tool including a shaft portion having a first end portion and a second end portion, the milling tool being rotatable about a rotation axis; a plurality of sensors attached to the shaft portion to detect an external force acting on the milling tool; a display device; and a management device. The plurality of sensors detect a first force acting on the milling tool in a first direction along the rotation axis, a second force acting on the milling tool in a direction along a plane normal to the rotation axis, and a load torque acting on the milling tool in a direction for preventing rotation of the milling tool. The management device causes the display device to display first information based on at least two of the first force, the second force, and the load torque.