The present disclosure relates to a carelessness determination method based on the analysis of a driver's biological state and an SCC association system and method using the same, which can determine a driver's carelessness state by using a line of sight of the driver, a change in the size of the pupil of the driver according to a vehicle speed, and external environment information and can forcedly change the subject of driving into a vehicle based on SCC when the driver's carelessness state is determined as a driver carelessness situation.