A current sensor comprising, in the same housing: a current detection part (100u, 100v, 100w) that detects a current flowing through a wiring line (110, 110u, 110v, 110w, 110u1, 110v1, 110w1, 110u2, 110v2, 110w2); a disconnection mechanism that disconnects the wiring line (110, 110u, 110v, 110w, 110u1, 110v1, 110w1, 110u2, 110v2, 110w2), the disconnection mechanism having a pressing member (104, 104u, 104v, 104w, 104v1, 104w1, 104u2, 104v2) that breaks the wiring line (110, 110u, 110v, 110w, 110u1, 110v1, 110w1, 110u2, 110v2, 110w2) by applying a pressing force to a part of the wiring line (110, 110u, 110v, 110w, 110u1, 110v1, 110w1, 110u2, 110v2, 110w2); and a drive circuit that drives the disconnection mechanism, wherein a current detection circuit included in the current detection part (100u, 100v, 100w) and the drive circuit are placed on the same substrate (103, 103u, 103w), the current detection part (100u, 100v, 100w) includes a magnetic core (101u, 101v, 101w, 101v1, 101w1, 101u2, 101v2) arranged in such a manner as to surround the wiring line (110, 110u, 110v, 110w, 110u1, 110v1, 110w1, 110u2, 110v2, 110w2) in a cross section of the wiring line (110, 110u, 110v, 110w, 110u1, 110v1, 110w1, 110u2, 110v2, 110w2), a Hall device (102, 102u, 102v, 102w, 102v1, 102w1, 102u2, 102v2) inserted in the magnetic core (101u, 101v, 101w, 101v1, 101w1, 101u2, 101v2) at a part in a circumferential direction of the magnetic core (101u, 101v, 101w, 101v1, 101w1, 101u2, 101v2), and an output circuit included in the current detection circuit, the output circuit outputting an output signal according to the current flowing through the wiring line (110, 110u, 110v, 110w, 110u1, 110v1, 110w1, 110u2, 110v2, 110w2) based on an output of the Hall device (102, 102u, 102v, 102w, 102v1, 102w1, 102u2, 102v2), wherein the magnetic core (101u, 101v, 101w, 101v1, 101w1, 101u2, 101v2) has a cut-out part, the pressing member (104, 104u, 104v, 104w, 104v1, 104w1, 104u2, 104v2) being passable through the cut-out part in an operation direction of the pressing member (104, 104u, 104v, 104w, 104v1, 104w1, 104u2, 104v2), and the pressing member (104, 104u, 104v, 104w, 104v1, 104w1, 104u2, 104v2) applies the pressing force to the wiring line (110, 110u, 110v, 110w, 110u1, 110v1, 110w1, 110u2, 110v2, 110w2) at a part exposed through the cut-out part. a current detection part (100u, 100v, 100w) that detects a current flowing through a wiring line (110, 110u, 110v, 110w, 110u1, 110v1, 110w1, 110u2, 110v2, 110w2); a disconnection mechanism that disconnects the wiring line (110, 110u, 110v, 110w, 110u1, 110v1, 110w1, 110u2, 110v2, 110w2), the disconnection mechanism having a pressing member (104, 104u, 104v, 104w, 104v1, 104w1, 104u2, 104v2) that breaks the wiring line (110, 110u, 110v, 110w, 110u1, 110v1, 110w1, 110u2, 110v2, 110w2) by applying a pressing force to a part of the wiring line (110, 110u, 110v, 110w, 110u1, 110v1, 110w1, 110u2, 110v2, 110w2); and a drive circuit that drives the disconnection mechanism, wherein a current detection circuit included in the current detection part (100u, 100v, 100w) and the drive circuit are placed on the same substrate (103, 103u, 103w), the current detection part (100u, 100v, 100w) includes a magnetic core (101u, 101v, 101w, 101v1, 101w1, 101u2, 101v2) arranged in such a manner as to surround the wiring line (110, 110u, 110v, 110w, 110u1, 110v1, 110w1, 110u2, 110v2, 110w2) in a cross section of the wiring line (110, 110u, 110v, 110w, 110u1, 110v1, 110w1, 110u2, 110v2, 110w2), a Hall device (102, 102u, 102v, 102w, 102v1, 102w1, 102u2, 102v2) inserted in the magnetic core (101u, 101v, 101w, 101v1, 101w1, 101u2, 101v2) at a part in a circumferential direction of the magnetic core (101u, 101v, 101w, 101v1, 101w1, 101u2, 101v2), and an output circuit included in the current detection circuit, the output circuit outputting an output signal according to the current flowing through the wiring line (110, 110u, 110v, 110w, 110u1, 110v1, 110w1, 110u2, 110v2, 110w2) based on an output of the Hall device (102, 102u, 102v, 102w, 102v1, 102w1, 102u2, 102v2), wherein the magnetic core (101u, 101v, 101w, 101v1, 101w1, 101u2, 101v2) has a cut-out part, the pressing member (104, 104u, 104v, 104w, 104v1, 104w1, 104u2, 104v2) being passable through the cut-out part in an operation direction of the pressing member (104, 104u, 104v, 104w, 104v1, 104w1, 104u2, 104v2), and the pressing member (104, 104u, 104v, 104w, 104v1, 104w1, 104u2, 104v2) applies the pressing force to the wiring line (110, 110u, 110v, 110w, 110u1, 110v1, 110w1, 110u2, 110v2, 110w2) at a part exposed through the cut-out part.