To provide a spectacle lens machining device capable of preventing the continuous occurrence of a defective lens due to the breakage of a drilling tool.

The spectacle lens machining device has a drilling mechanism to machine a hole for mounting a rimless frame to a spectacle lens by the drilling tool. The device is provided with a detecting means for detecting the presence or the absence of the breakage of the drilling tool. The detecting means is provided with a moving means for bringing a contact shoe brought into contact with the tip of the drilling tool into relative contact with the tip of the drilling tool, and a detector for electrically detecting the movement of the contact shoe. The detector is arranged to the outside of a machining chamber in which the drilling tool is arranged.