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 disposed at positions around the opening , the plurality of joints 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 (L1) connecting the first joint and the second joint and a second straight line (L2) 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 (L1) and the second straight line (L2) 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 disposed at positions around the opening , the plurality of joints 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 (L1) connecting the first joint and the second joint and a second straight line (L2) 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 (L1) and the second straight line (L2) is located on the buffer when viewed from one side in a joining direction between the case and the lid body . <EOS>