An infrared sensor comprising: a pyroelectric element; an IC device configured to process an output signal of said pyroelectric element; and a surface-mounted package configured to house said pyroelectric element and said IC device, wherein said package includes a package body and a package lid, said package body comprising a substrate made of a dielectric material, a circuit wiring, and a plurality of external connection electrodes, said circuit wiring and the plurality of said external connection electrodes being made of a metal material and formed on said substrate, said package lid being configured to transmit infrared rays to be detected by said pyroelectric element, said package lid being bonded to said package body in a manner of enclosing with said package body said pyroelectric element and said IC device, said package body having a surface and being provided with plural recessed parts (41a,41b) arranged in tiers in the surface of said package body, said IC device being mounted on a bottom of a lower recessed part of said recessed parts (41a,41b), said pyroelectric element being mounted on a bottom of an upper recessed part of said recessed parts (41a,41b) closer to the surface of said package body than said lower recessed part is, so as to extend across said lower recessed part and to be away from said IC device in a thickness direction thereof, said package body including an output wiring and a shielding member, said output wiring being configured to electrically connect an output terminal of said IC device to said external connection electrodes, said shielding member being interposed between said pyroelectric element and said output wiring, and said IC device including a specific part adapted in use to receive a ground potential or a constant potential, and said shielding member being electrically connected to said specific part of said IC device, wherein said IC device has a main surface provided with a circuit part and a rear surface opposite to said main surface, and said IC device is mounted on said bottom of said lower recessed part such that said main surface and said rear surface face said bottom of said lower recessed part and said pyroelectric element, respectively. a pyroelectric element; an IC device configured to process an output signal of said pyroelectric element; and a surface-mounted package configured to house said pyroelectric element and said IC device, wherein said package includes a package body and a package lid, said package body comprising a substrate made of a dielectric material, a circuit wiring, and a plurality of external connection electrodes, said circuit wiring and the plurality of said external connection electrodes being made of a metal material and formed on said substrate, said package lid being configured to transmit infrared rays to be detected by said pyroelectric element, said package lid being bonded to said package body in a manner of enclosing with said package body said pyroelectric element and said IC device, said package body having a surface and being provided with plural recessed parts (41a,41b) arranged in tiers in the surface of said package body, said IC device being mounted on a bottom of a lower recessed part of said recessed parts (41a,41b), said pyroelectric element being mounted on a bottom of an upper recessed part of said recessed parts (41a,41b) closer to the surface of said package body than said lower recessed part is, so as to extend across said lower recessed part and to be away from said IC device in a thickness direction thereof, said package body including an output wiring and a shielding member, said output wiring being configured to electrically connect an output terminal of said IC device to said external connection electrodes, said shielding member being interposed between said pyroelectric element and said output wiring, and said IC device including a specific part adapted in use to receive a ground potential or a constant potential, and said shielding member being electrically connected to said specific part of said IC device, wherein said IC device has a main surface provided with a circuit part and a rear surface opposite to said main surface, and said IC device is mounted on said bottom of said lower recessed part such that said main surface and said rear surface face said bottom of said lower recessed part and said pyroelectric element, respectively.