To provide a soiled diaper sensing system and a diaper capable of sensing soil accurately from outside by using a plurality of elements made inexpensively.

The soiled diaper sensing system comprises the diaper 10 including a water absorbent layer retaining excrement and having a water-absorbing property, a cover layer for wrapping the water absorbent layer, and the plurality of elements which are provided on the water absorbent layer, transmit prescribed signals, and halt the transmission function when detecting excrement, a receiving means for receiving the prescribed signals transmitted from the elements, a means for counting the number of operating elements from the prescribed signals received by the receiving means, and a display means for displaying to encourage to change the diaper if the number of operating elements counted by the means for counting the number of operating elements is less than a prescribed value.