Flexible resin composition and sealing part for waterproof connector

To provide a sealing part for a waterproof connector, which can maintain good waterproof property and can also decrease the fitting force between the female connector housing and the male connector housing, using a thermoplastic resin having recyclability and excellent in productivity and workability. A flexible resin composition comprising 100 parts by weight of a polyester-based or polyolefinic elastomer having a Shore A hardness of 30 to less than 80 and 0.1 to 10 parts by weight of ethylenebisstearic acid amide or ethylenebisoleic acid amide; and a sealing part to be attached to a housing for waterproofing a connector, which is obtained by forming the above-mentioned flexible resin composition.