A sensor, comprising a first substrate (41) including a first semiconductor layer (310) including a first avalanche photodiode (21) including a first cathode region (101) and a first anode region (105); and a first isolation region (108), a first wiring layer (41, 311) including a first wiring; a first via (104), wherein the first cathode region (101) is electrically connected to the first wiring through the first via (104); a second wiring; and a second via (106), wherein the first anode region (105) is electrically connected to the second wiring through the second via (106); and a second substrate (42) stacked on the first substrate, the second substrate including a second wiring layer (42, 610) including a third wiring directly bonded to the first wiring; and a fourth wiring directly bonded to the second wiring; and a second semiconductor layer (610), wherein the first anode region (105) is disposed between the first cathode region (101) and the first isolation region (108).