A system for determining heart failure exacerbation includes a wearable device measuring biological data and motion data of a subject, and a server connectable to the wearable device to: acquire the biological data and motion data at each time point in a predetermined period; calculate a parameter related to a heart based on the biological data; calculate an activity amount based on the motion data; identify active time points where the calculated activity amounts are equal to or greater than a predetermined value; identify specific parameters at delayed time points when a predetermined time has elapsed from the active time points; and calculate an index value related to the heart failure exacerbation based on a relationship between the activity amounts at the active time points and the specific parameters at the delayed time points.