PROBLEM TO BE SOLVED: To provide an on-bed determination device reducing occurrences of a false detection and an erroneous determination.SOLUTION: An on-bed determination device 100 includes: a load sensor 11 that is disposed on a bed 2 and detects a change in the load on the bed 2; a body motion determination section 14 that, when the load on the bed 2 is a preset load or more, determines whether or not there is the body motion of an object on the bed 2; and an on-bed determination section 16 that, when there is the body motion within a prescribed time after the load has been detected, determines that a person 1 has been present on the bed 2 from when the load has been detected till the body motion has been determined.