Provide is an aircraft water tank which is advantageous in omitting a coating process for preventing an adhesive, which attaches the inner liner to the skirt portion, from directly coming into contact with water and for reducing costs. A lid (34) is joined to an opening portion (18) via internal threads (36) and external threads (50), and an O-ring (52) is compressed, so that the opening portion (18) is liquid-tightly sealed, which forms a sealed water storage space (12A) in a tank body (12). The portion of the lid (34) that compresses the O-ring (52) is a corner portion formed by an end surface (4402) of an annular plate portion (44) and an outer peripheral surface (4602) of a tube portion (46). The portion of an inner liner (22) that compresses the O-ring (52) is a portion of the inner liner 22 attached to an inclined surface (40). An end portion (2202) of the inner liner (22) attached to the surface of a bulging portion (38) is located outside the water storage space (12A).
