A diaphragm pump for reducing the pressure ripple of a discharged gas is provided. A diaphragm pump 1 which sends out a gas by the volume variation of a pump room 12 comprises: a discharge valve 30, allowing the outflow of a gas from the pump room 12 while prohibiting the flow toward the opposite direction； an air room 41 for the air to flow out from the pump room 12 through the discharge valve 30； a discharge port 43 for discharge the air outside of the diaphragm pump 30； and a through hole portion 44 for limiting the quantity of the air flowing toward the discharge port 43 from the air room 41.提供一種減少所吐出之氣體的壓力漣波(pressure ripple)之膜片泵作為課題。在解決手段上，膜片泵1，係利用泵室12之容積變化而輸送氣體的泵，具備有：吐出閥30，容許從泵室12流出的氣體之流動且禁止朝其相反方向之流動；空氣室41，係讓通過吐出閥30並從泵室12流出的氣體流入；吐出口43，使氣體朝膜片泵1之外部吐出；及貫通孔部44，限制從空氣室41朝吐出口43流動的氣體之流量。
