An effective component generation device comprising: an internal component including a discharger that generates an effective component; and a case having a box shape having a discharge port through which the effective component is discharged, the case housing the internal component, wherein the case includes a metal body including a bottom plate and peripheral walls, the bottom plate and the peripheral walls surrounding at least the discharger and the internal component; the metal body includes a seamless portion at a corner portion between two surfaces of adjacent peripheral walls oriented in different directions; and a lid body joined to the case, wherein the case has an opening provided at a position different from a position of the discharge port; and the lid body is joined to the case, closing the opening in a state where the internal component is housed between the lid body and the case; characterized in that the case and the lid body are joined to each other at a plurality of joints (81, 82, 83, 84, 85, 86, 87, 88, 89) disposed at positions around the opening, the plurality of joints (81, 82, 83, 84, 85, 86, 87, 88, 89) including at least a first joint, a second joint, a third joint and a fourth joint, the first joint, the second joint, the third joint and the fourth joint are disposed in such a manner that a first straight line connecting the first joint and the second joint and a second straight line connecting the third joint and the fourth joint intersect each other in the opening; and the effective component generation device further comprises a buffer sandwiched between the lid body and a part of the internal component, wherein an intersection of the first straight line and the second straight line is located on the buffer when viewed from one side in a joining direction between the case and the lid body. an internal component including a discharger that generates an effective component; and a case having a box shape having a discharge port through which the effective component is discharged, the case housing the internal component, wherein the case includes a metal body including a bottom plate and peripheral walls, the bottom plate and the peripheral walls surrounding at least the discharger and the internal component; the metal body includes a seamless portion at a corner portion between two surfaces of adjacent peripheral walls oriented in different directions; and a lid body joined to the case, wherein the case has an opening provided at a position different from a position of the discharge port; and the lid body is joined to the case, closing the opening in a state where the internal component is housed between the lid body and the case; characterized in that the case and the lid body are joined to each other at a plurality of joints (81, 82, 83, 84, 85, 86, 87, 88, 89) disposed at positions around the opening, the plurality of joints (81, 82, 83, 84, 85, 86, 87, 88, 89) including at least a first joint, a second joint, a third joint and a fourth joint, the first joint, the second joint, the third joint and the fourth joint are disposed in such a manner that a first straight line connecting the first joint and the second joint and a second straight line connecting the third joint and the fourth joint intersect each other in the opening; and the effective component generation device further comprises a buffer sandwiched between the lid body and a part of the internal component, wherein an intersection of the first straight line and the second straight line is located on the buffer when viewed from one side in a joining direction between the case and the lid body.