A window of an aircraft having electromagnetic shielding performance and environment-resistant sealing performance, an aircraft, and an assembly method for a window of an aircraft are provided. A conductive seal member (60) is provided so as to face and surround the peripheral side surface of a window panel and is sandwiched between a conductive film (41) and an outer retainer (22). In the conductive seal member (60), thin wire materials (62) made of a conductive material such as aluminum are embedded in a seal member body (61) made of a material, such as silicone rubber, having an electric insulating property, waterproofness and pliability. An electromagnetic shielding effect, and environment-resistant sealing properties such as an electric insulating property and waterproofness can be both ensured by the conductive seal member (60).