PROBLEM TO BE SOLVED: To prevent dust or the like from attaching to an inner wall of a concave portion of an insulation member.SOLUTION: A discharge unit (20) includes an insulation member (41) supporting a discharge electrode (70) and a counter electrode (60). The insulation member (41) has a base portion (44) supporting a counter electrode (60) at its periphery, a concave portion (46) concave in a direction intersecting air flow flowing through a ventilation passage (27) in the base portion (44), and a support portion (47) protruding from a bottom portion of the concave portion (46) out of an opening face of the concave portion (46) and supporting the discharge electrode (70).SELECTED DRAWING: Figure 13COPYRIGHT: (C)2016,JPO&INPIT【課題】絶縁部材の凹部の内壁に塵埃等が付着してしまうことを防止する。【解決手段】放電ユニット(20)は、放電電極(70)と対向電極(60)とを支持する絶縁部材(41)を備える。絶縁部材(41)は、周囲に対向電極(60)を支持する基台部(44)と、基台部(44)において通風路(27)を流れる空気流れと交差する方向に凹んだ凹部(46)と、凹部(46)の底部から凹部(46)の開放面より外方に突出し、放電電極(70)を支持する支持部(47)とを有している。【選択図】図13
