A cover material fixing device includes: a first fixing member that is formed in a plate shape so that the first fixing member is connected to a first cover material at a first connection portion of one end portion and has an insertion portion formed at the other end portion; and a second fixing member that is disposed on a groove portion of a fixed member, is provided along the first fixing member, and includes a holding portion holding the insertion portion. The insertion portion is inserted and engaged with the holding portion so that the first cover material is fixed to the fixed member and the insertion portion of the first fixing member includes a rotation restricting portion for the holding portion.