To provide an excrement sampling device which does not make the evacuation opening of a toilet stool significantly narrower and, at the same time, the excrement sampling arm of which can be washed sufficiently even when the device is attached to the stool.

A supporting means 11 which is attached to the toilet stool 100 and supports the excrement sampling arm 20 is only provided on one end side of the arm 20. In addition, a nozzle 15 which jets washing water W to wash the arm 20 is attached to the supporting means 11.