A watching assistance system that assists watching over a subject on a bed, the watching assistance system includes: a detector configured to detect a position of a predetermined region of the subject from the image captured by an imaging device; a determination unit configured to determine whether the subject raises oneself up based on the position at which the predetermined region of the subject is detected; and an output unit configured to provide notification when the determination unit determines that the subject raises oneself up. Based on a bed region in the image, a lying region is set to an existing range of a predetermined region at a lying time, and a raising-up region is set to an existing range of the predetermined region at a raising-up time. The lying region and the raising-up region are disposed at an interval. The determination unit determines that the subject raises oneself up when a condition that predetermined region of the subject is detected in the raising-up region after the predetermined region of the subject is detected in the lying region is satisfied.