A sensor device for welding, comprising at least: a sensor unit configured to measure states of workpieces to be welded together or a distance to the workpieces; and a container including a housing portion and a shielding portion, the housing portion being adapted to house the sensor unit, and the shielding portion being adapted to shield radiation heat directed toward the housing portion among radiation heat generated while the workpieces are welded together, wherein: the shielding portion is made of a material with lower thermal conductivity than that of the housing portion, the shielding portion is a shielding member attached to the housing portion as a housing case, the sensor device being characterised in that: the shielding member has formed therein a plate-like portion and an attachment portion, the plate-like portion extending so as to shield the radiation heat, and the attachment portion being arranged on a rear face side of the plate-like portion that is opposite to a side where the workpieces are to be welded together and being adapted to attach the shielding member to the housing case, the shielding member is attached on the rear face side of the plate-like portion to the housing case via the attachment portion, a gap is formed between the plate-like portion of the shielding member and the housing case in a state in which the shielding member is attached to the housing case, the housing case has attached thereto an elastic member, the elastic member being adapted to urge the shielding member toward a side where the workpieces are to be welded together in a state in which the shielding member is attached to the housing case, and the gap is formed between the housing case and the plate-like portion of the shielding member in a state in which the shielding member is urged by the elastic member. a sensor unit configured to measure states of workpieces to be welded together or a distance to the workpieces; and a container including a housing portion and a shielding portion, the housing portion being adapted to house the sensor unit, and the shielding portion being adapted to shield radiation heat directed toward the housing portion among radiation heat generated while the workpieces are welded together, wherein: the shielding portion is made of a material with lower thermal conductivity than that of the housing portion, the shielding portion is a shielding member attached to the housing portion as a housing case, the sensor device being characterised in that: the shielding member has formed therein a plate-like portion and an attachment portion, the plate-like portion extending so as to shield the radiation heat, and the attachment portion being arranged on a rear face side of the plate-like portion that is opposite to a side where the workpieces are to be welded together and being adapted to attach the shielding member to the housing case, the shielding member is attached on the rear face side of the plate-like portion to the housing case via the attachment portion, a gap is formed between the plate-like portion of the shielding member and the housing case in a state in which the shielding member is attached to the housing case, the housing case has attached thereto an elastic member, the elastic member being adapted to urge the shielding member toward a side where the workpieces are to be welded together in a state in which the shielding member is attached to the housing case, and the gap is formed between the housing case and the plate-like portion of the shielding member in a state in which the shielding member is urged by the elastic member. the shielding portion is made of a material with lower thermal conductivity than that of the housing portion, the shielding portion is a shielding member attached to the housing portion as a housing case, the sensor device being characterised in that: the shielding member has formed therein a plate-like portion and an attachment portion, the plate-like portion extending so as to shield the radiation heat, and the attachment portion being arranged on a rear face side of the plate-like portion that is opposite to a side where the workpieces are to be welded together and being adapted to attach the shielding member to the housing case, the shielding member is attached on the rear face side of the plate-like portion to the housing case via the attachment portion, a gap is formed between the plate-like portion of the shielding member and the housing case in a state in which the shielding member is attached to the housing case, the housing case has attached thereto an elastic member, the elastic member being adapted to urge the shielding member toward a side where the workpieces are to be welded together in a state in which the shielding member is attached to the housing case, and the gap is formed between the housing case and the plate-like portion of the shielding member in a state in which the shielding member is urged by the elastic member.