The present invention relates to verifying the suitability of a tool and diagnosing a spindle for a machining center on which different tools are mounted. Provided are a machining center spindle diagnosis apparatus and method configured to monitor a change of a tool in the machining center; when the change of the tool is recognized, control the machining center to idle the spindle; acquire sensor data from a sensor installed on the machining center during the idling of the spindle; input the acquired sensor data to a tool verifying model pre-trained by a machine learning technology to verify suitability of the tool; and when the tool is verified to be suitable, inputting the acquired sensor data to a spindle diagnosing model pre-trained by the machine learning technology to diagnose an operating state of the spindle.