Abstract: A fluid outlet opening/closing mechanism and a fluid storing member equipped with this mechanism including a valve seat having a portion formed of a magnetic material, housed in the fluid storing member and adapted to be attached to an outlet portion of the fluid storing member, and a valve member having a portion formed of a magnetic material and adapted to be seated on the valve seat. At least either of the magnetic portions respectively of the valve seat and of the valve member is constituted by a material capable of generating a magnetic field.