The invention relates to a apparatus and method for determining a driving state. The apparatus includes a jerk calculator configured to determine a minimum prediction jerk generated in an interval until an ego vehicle arrives at a location of a preceding vehicle, using location, velocity, and acceleration information of the ego vehicle at a current time and location, velocity, and acceleration information of the preceding vehicle and determine a permission jerk of a driver of the ego vehicle, a determiner configured to determine whether the minimum prediction jerk is greater than the permission jerk of the driver and determine a careless driving state based on a driving operation state of the driver when the minimum prediction jerk is greater than the permission jerk of the driver, and a signal processor configured to output an alert when it is determined as the careless driving state.