A door trim installed in a vehicle includes an upper board and a lower board. The upper board includes a mounting boss. The lower board includes a body and a mounting flange. The body defines a lower portion of the door trim. The mounting flange extends upward from an upper edge of the body and includes a mounting hole. The mounting flange is disposed behind a back face of the upper board. The mounting boss protrudes from the back face of the upper board toward the mounting hole of the mounting flange. The mounting hole includes a through hole portion and a slot portion. The mounting boss is inserted in the through hole portion. The slot portion extends from a front section of a hole edge of the through hole portion toward a front of the vehicle to communicate with the through hole portion.