To provide an intake valve for a drainage pipe, not affected by an attaching direction, capable of reducing limitation when installed, capable of reducing constitutive components, capable of exhibiting a valve function by simple structure, and easily inspected and cleaned.

This intake valve 10 for the drainage pipe includes a cylindrical valve casing 12 and a valve member 14, and is fit around the drainage pipe via a connection port 22, to release a negative pressure generated in an inside of the drainage pipe. An intake port 20 is formed in one end of the valve casing 12, and the intake port 20 is connected with the valve member 14 that is an elastic and flexible cylindrical film. The valve member 14 is formed with a closing part 28 attached with a habit to bring inner walls thereof into face contact. The closing part 28 is closed usually, in the intake valve 10 for the drainage pipe, to close the communication with the intake port 20. On the other hand, the closing part 28 is opened, when the negative pressure is generated in the drainage pipe, to be communicated with the intake port 20. An opening and closing operation of the intake port 20 is carried out by an elastic characteristic of the closing part 28.