Pressure valve and electrolytic capacitor

A pressure valve to be arranged in a seal member configured to seal a casing accommodating therein a capacitor element, in such a manner that a base end of the pressure valve is positioned inside the casing whereas a tip of the pressure valve is positioned outside the casing, the pressure valve comprising

• a tapered portion having a tapered shape, wherein
• a top portion of the tapered portion has a slit which is state-changeable between an open-state and a close-state through elastic deformation;
• and
• the slit is formed in a tapered shape such that a width of one end portion of the top portion relative to its thickness direction is wider than another end portion,
• the slit keeps its close-state while a casing internal pressure is less than a certain value, whereas
• the slit changes its state to the open-state when the casing internal pressure reaches the certain value, thereby releasing the casing internal pressure by communicating the inside and the outside of the casing.