A magnetic detection device (1, 2, 3) comprising: a substrate (S1, S2); a magneto-impedance element, MI element (M1, M61, M62) disposed on the substrate (S1, S2) and comprising a magneto-sensitive wire (W1, W61, W62) and a detection coil (C1, C61, C62), the magneto-sensitive wire (W1, W61, W62) sensing an external magnetic field component in an extending direction, the detection coil (C1, C61, C62) looping around the magneto-sensitive wire (W1, W61, W62); and a magnetic field deflector (F1, F5, F6) of which at least a part is disposed on the substrate (S1, S2) or in the substrate (S1, S2), the magnetic field deflector (F1, F5, F6) deflecting an external magnetic field around the magneto-sensitive wire (W1, W61, W62), characterized in that the magnetic field deflector (F1, F5, F6) comprising: a core part (F10, F510, F520, F620) composed of a nonmagnetic material; and a shell part (F11, F511, F521, F621) composed of a soft magnetic material, the shell part (F11, F511, F521, F621) covering an outer side of at least a part of the core part (F10, F510, F520, F620), wherein the core part (F10, F510, F520, F620) has a column-like shape or circular cone-like shape extending in a direction orthogonal to the magneto-sensitive wire (W1, W61, W62), at least a part of the shell part (F11, F511, F521, F621) is formed on a top surface of the core part (F10, F510, F520, F620) as an end surface at the magneto-sensitive wire side, and the magnetic field deflector (F1, F5, F6) deflecting the external magnetic field around the magneto-sensitive wire (W1, W61, W62) in such a way that a magnetic field component of the external magnetic field in a direction orthogonal to the extending direction is deflected to the extending direction. a substrate (S1, S2); a magneto-impedance element, MI element (M1, M61, M62) disposed on the substrate (S1, S2) and comprising a magneto-sensitive wire (W1, W61, W62) and a detection coil (C1, C61, C62), the magneto-sensitive wire (W1, W61, W62) sensing an external magnetic field component in an extending direction, the detection coil (C1, C61, C62) looping around the magneto-sensitive wire (W1, W61, W62); and a magnetic field deflector (F1, F5, F6) of which at least a part is disposed on the substrate (S1, S2) or in the substrate (S1, S2), the magnetic field deflector (F1, F5, F6) deflecting an external magnetic field around the magneto-sensitive wire (W1, W61, W62), characterized in that the magnetic field deflector (F1, F5, F6) comprising: a core part (F10, F510, F520, F620) composed of a nonmagnetic material; and a shell part (F11, F511, F521, F621) composed of a soft magnetic material, the shell part (F11, F511, F521, F621) covering an outer side of at least a part of the core part (F10, F510, F520, F620), wherein the core part (F10, F510, F520, F620) has a column-like shape or circular cone-like shape extending in a direction orthogonal to the magneto-sensitive wire (W1, W61, W62), at least a part of the shell part (F11, F511, F521, F621) is formed on a top surface of the core part (F10, F510, F520, F620) as an end surface at the magneto-sensitive wire side, and the magnetic field deflector (F1, F5, F6) deflecting the external magnetic field around the magneto-sensitive wire (W1, W61, W62) in such a way that a magnetic field component of the external magnetic field in a direction orthogonal to the extending direction is deflected to the extending direction. a core part (F10, F510, F520, F620) composed of a nonmagnetic material; and a shell part (F11, F511, F521, F621) composed of a soft magnetic material, the shell part (F11, F511, F521, F621) covering an outer side of at least a part of the core part (F10, F510, F520, F620), wherein the core part (F10, F510, F520, F620) has a column-like shape or circular cone-like shape extending in a direction orthogonal to the magneto-sensitive wire (W1, W61, W62), at least a part of the shell part (F11, F511, F521, F621) is formed on a top surface of the core part (F10, F510, F520, F620) as an end surface at the magneto-sensitive wire side, and the magnetic field deflector (F1, F5, F6) deflecting the external magnetic field around the magneto-sensitive wire (W1, W61, W62) in such a way that a magnetic field component of the external magnetic field in a direction orthogonal to the extending direction is deflected to the extending direction.