A jet solder bath (20; 20A) for performing soldering by jetting molten solder to bring the molten solder into contact with a substrate, the jet solder bath (20; 20A) comprising: a first jet nozzle configured to jet the molten solder by a first jet pump; and a second jet nozzle that is arranged at a downstream side of the first jet nozzle along a substrate-carrying direction and configured to jet the molten solder by a second jet pump, a downstream-forming portion configured to include a downstream forming plate configured to form the molten solder from the second jet nozzle to the downstream side, a shaft configured to rotate the downstream forming plate with respect to the second jet nozzle, a solder-flow-changing plate attached to a downstream end of the downstream-forming plate, a support plate attached to the downstream forming plate at a position sandwiching the downstream forming plate with respect to the solder-flow-changing plate, screws (46e, 46e, 46e) for fixing the solder-flow-changing plate, the downstream forming plate and the support plate in this order, a protrusion portion configured to protrude from the support plate and a bolt inserted into a screw hole formed in the protrusion portion, the solder-flow-changing plate is provided with vertically long holes (46c1), and the height of the solder-flow-changing plate with respect to the downstream forming plate is vertically changeable by changing the height at which the screws are screwed with respect to the long holes (46c1), wherein the first jet nozzle includes: a first nozzle body; and a first solder-flow-forming plate that is provided at an upper end of the first nozzle body and has a plurality of jet holes, wherein the second jet nozzle includes: a second nozzle body; and a second solder-flow-forming plate that is provided at an upper end of the second nozzle body and has a plurality of jet holes, and wherein a guide plate having a plurality of holes is provided on at least any of an upstream side of the first nozzle body in the substrate-carrying direction, a downstream side of the second nozzle body, and an interval between the first nozzle body and the second nozzle body. a first jet nozzle configured to jet the molten solder by a first jet pump; and a second jet nozzle that is arranged at a downstream side of the first jet nozzle along a substrate-carrying direction and configured to jet the molten solder by a second jet pump, a downstream-forming portion configured to include a downstream forming plate configured to form the molten solder from the second jet nozzle to the downstream side, a shaft configured to rotate the downstream forming plate with respect to the second jet nozzle, a solder-flow-changing plate attached to a downstream end of the downstream-forming plate, a support plate attached to the downstream forming plate at a position sandwiching the downstream forming plate with respect to the solder-flow-changing plate, screws (46e, 46e, 46e) for fixing the solder-flow-changing plate, the downstream forming plate and the support plate in this order, a protrusion portion configured to protrude from the support plate and a bolt inserted into a screw hole formed in the protrusion portion, the solder-flow-changing plate is provided with vertically long holes (46c1), and the height of the solder-flow-changing plate with respect to the downstream forming plate is vertically changeable by changing the height at which the screws are screwed with respect to the long holes (46c1), wherein the first jet nozzle includes: a first nozzle body; and a first solder-flow-forming plate that is provided at an upper end of the first nozzle body and has a plurality of jet holes, wherein the second jet nozzle includes: a second nozzle body; and a second solder-flow-forming plate that is provided at an upper end of the second nozzle body and has a plurality of jet holes, and wherein a guide plate having a plurality of holes is provided on at least any of an upstream side of the first nozzle body in the substrate-carrying direction, a downstream side of the second nozzle body, and an interval between the first nozzle body and the second nozzle body. a first nozzle body; and a first solder-flow-forming plate that is provided at an upper end of the first nozzle body and has a plurality of jet holes, wherein the second jet nozzle includes: a second nozzle body; and a second solder-flow-forming plate that is provided at an upper end of the second nozzle body and has a plurality of jet holes, and wherein a guide plate having a plurality of holes is provided on at least any of an upstream side of the first nozzle body in the substrate-carrying direction, a downstream side of the second nozzle body, and an interval between the first nozzle body and the second nozzle body. a second nozzle body; and a second solder-flow-forming plate that is provided at an upper end of the second nozzle body and has a plurality of jet holes, and wherein a guide plate having a plurality of holes is provided on at least any of an upstream side of the first nozzle body in the substrate-carrying direction, a downstream side of the second nozzle body, and an interval between the first nozzle body and the second nozzle body.