A sealing device suitable to be provided between a reciprocating shaft and an inner surface of a shaft hole in which the reciprocating shaft is provided, wherein the sealing device comprises: an oil seal member comprising a liquid-side rigid ring made of a rigid body and suitable to be provided inside the shaft hole , and a liquid-side elastic ring made of an elastic body and attached to the liquid-side rigid ring , the liquid-side elastic ring having formed thereon an oil lip that is provided more radially inward than the liquid-side rigid ring and is suitable to slidably make sealing contact with the reciprocating shaft ; a dust seal member comprising an atmosphere-side rigid ring made of a rigid body and detachably fitted in the liquid-side rigid ring , and an atmosphere-side elastic ring made of an elastic body and fixed to the atmosphere-side rigid ring , the atmosphere-side elastic ring having formed thereon a dust lip that is provided more radially inward than the atmosphere-side rigid ring and is suitable to slidably contact the reciprocating shaft ; and an intermediate rigid ring that is made of a rigid body, is detachably fitted in a concave portion formed radially inward of the atmosphere-side rigid ring and in a concave portion formed radially inward of the liquid-side elastic ring , is provided between the liquid-side elastic ring and the atmosphere-side elastic ring in a direction parallel to the axial direction of the reciprocating shaft , and reinforces the liquid-side elastic ring , characterized in that at least one groove is formed in the concave portion formed radially inward of the liquid-side elastic ring , and a protrusion press-fitted in the groove is formed on the intermediate rigid ring . an oil seal member comprising a liquid-side rigid ring made of a rigid body and suitable to be provided inside the shaft hole , and a liquid-side elastic ring made of an elastic body and attached to the liquid-side rigid ring , the liquid-side elastic ring having formed thereon an oil lip that is provided more radially inward than the liquid-side rigid ring and is suitable to slidably make sealing contact with the reciprocating shaft ; a dust seal member comprising an atmosphere-side rigid ring made of a rigid body and detachably fitted in the liquid-side rigid ring , and an atmosphere-side elastic ring made of an elastic body and fixed to the atmosphere-side rigid ring , the atmosphere-side elastic ring having formed thereon a dust lip that is provided more radially inward than the atmosphere-side rigid ring and is suitable to slidably contact the reciprocating shaft ; and an intermediate rigid ring that is made of a rigid body, is detachably fitted in a concave portion formed radially inward of the atmosphere-side rigid ring and in a concave portion formed radially inward of the liquid-side elastic ring , is provided between the liquid-side elastic ring and the atmosphere-side elastic ring in a direction parallel to the axial direction of the reciprocating shaft , and reinforces the liquid-side elastic ring , characterized in that at least one groove is formed in the concave portion formed radially inward of the liquid-side elastic ring , and a protrusion press-fitted in the groove is formed on the intermediate rigid ring . <EOS>