A rack mount device includes: a support rail which is provided in a rack and which extends in a front-rear direction of the rack; an electronic device which is housed in the rack along the support rail and which is supported by the support rail; an upper support portion which is provided in the rack and which is arranged at a position higher than the support rail; and a holding member which extends obliquely downward from the upper support portion to a side to which the electronic device is drawn out and which holds the electronic device outside of the rack in a state in which the electronic device has been drawn out from the rack along the support rail.