A tool-life determination device includes: a test-workpiece supporter having a cutting tool attached thereto, rotating the cutting tool, and supporting a test workpiece disposed in a processable range of the cutting tool of a working machine that performs a process while changing a relative position between the cutting tool and a workpiece; a load sensor disposed between the test-workpiece supporter and a base of the working machine fixed to an installation surface and detecting a load applied to the test workpiece; a storage unit storing a load pattern acting on the test workpiece and detected by the load sensor when the test workpiece is processed using a new cutting tool; and a determination unit determining an abrasion status of the cutting tool by comparing the load pattern with the load acting on the test workpiece at an appropriate timing during an actual process performed on the workpiece.