An assembly-type vehicle component (1A, 1B) comprising: a mounting member configured to be mounted to a vehicle body side; and functional members (3A, 3B) having a predetermined function, wherein the mounting member is provided with a detachment preventing engagement portion configured to be engaged with an engagement portion (31A, 31B) of the functional members (3A, 3B) to bring the functional members (3A, 3B) into a detachment-prevented state, the functional members (3A, 3B) include, as the engagement portion (31A, 31B), an elastic engagement portion (31A, 31B) configured to, when being caused to approach in a predetermined direction toward the detachment preventing engagement portion, ride over the detachment preventing engagement portion while being elastically deformed in a direction perpendicular to the predetermined direction, and after riding over the detachment preventing engagement portion, be elastically restored to be engaged with the detachment preventing engagement portion, thereby establishing the detachment-prevented state with respect to the mounting member, the functional members (3A, 3B) including: a first functional member in which the elastic deformation of the elastic engagement portion is caused in a first elastic deformation direction (2z2); and a second functional member in which the elastic deformation of the elastic engagement portion is caused in a second elastic deformation direction (2z1) opposite to the first elastic deformation direction (2z2), each of the first functional member and the second functional member being capable of being brought into the detachment-prevented state with respect to the mounting member, the mounting member includes: a first rattling preventing protrusion protruding in the second elastic deformation direction (2z1) and configured to press, in the second elastic deformation direction (2z1), the first functional member in the detachment-prevented state; and a second rattling preventing protrusion protruding in the first elastic deformation direction (2z2) and configured to press, in the first elastic deformation direction (2z2), the second functional member in the detachment-prevented state, the first functional member includes a first reception portion configured to receive the second rattling preventing protrusion so as not to cause pressing to the first functional member when the first functional member is in the detachment-prevented state with respect to the mounting member, and the second functional member includes a second reception portion configured to receive the first rattling preventing protrusion so as not to cause pressing to the second functional member when the second functional member is in the detachment-prevented state with respect to the mounting member. a mounting member configured to be mounted to a vehicle body side; and functional members (3A, 3B) having a predetermined function, wherein the mounting member is provided with a detachment preventing engagement portion configured to be engaged with an engagement portion (31A, 31B) of the functional members (3A, 3B) to bring the functional members (3A, 3B) into a detachment-prevented state, the functional members (3A, 3B) include, as the engagement portion (31A, 31B), an elastic engagement portion (31A, 31B) configured to, when being caused to approach in a predetermined direction toward the detachment preventing engagement portion, ride over the detachment preventing engagement portion while being elastically deformed in a direction perpendicular to the predetermined direction, and after riding over the detachment preventing engagement portion, be elastically restored to be engaged with the detachment preventing engagement portion, thereby establishing the detachment-prevented state with respect to the mounting member, the functional members (3A, 3B) including: a first functional member in which the elastic deformation of the elastic engagement portion is caused in a first elastic deformation direction (2z2); and a second functional member in which the elastic deformation of the elastic engagement portion is caused in a second elastic deformation direction (2z1) opposite to the first elastic deformation direction (2z2), each of the first functional member and the second functional member being capable of being brought into the detachment-prevented state with respect to the mounting member, the mounting member includes: a first rattling preventing protrusion protruding in the second elastic deformation direction (2z1) and configured to press, in the second elastic deformation direction (2z1), the first functional member in the detachment-prevented state; and a second rattling preventing protrusion protruding in the first elastic deformation direction (2z2) and configured to press, in the first elastic deformation direction (2z2), the second functional member in the detachment-prevented state, the first functional member includes a first reception portion configured to receive the second rattling preventing protrusion so as not to cause pressing to the first functional member when the first functional member is in the detachment-prevented state with respect to the mounting member, and the second functional member includes a second reception portion configured to receive the first rattling preventing protrusion so as not to cause pressing to the second functional member when the second functional member is in the detachment-prevented state with respect to the mounting member.