PURPOSE: To mount a bicycle safely and positively in spite of a relatively simple device by using a ladder.

CONSTITUTION: A bicycle mounting device in an automobile is constituted of a supporting metal fitting 1 fitted to a ladder formed of a pipe member, a supporting rod 13 provided in line with the supporting metal fitting 1, and a supporting member 11 fitted to the supporting rod 13. The supporting metal fitting 1 is constituted of a pair of opposed sheet metals. One opposed face has a recessed groove 6 into which the pipe member of the ladder can be fitted, and bolt holes 4, 11 are provided in the opposed positions. The intermediate part of the recessed groove 6 has through holes 7, 8, 9 bored in the opposed positions of each sheet metal. The supporting rod 13 can be held between both sheet metals. The supporting rod 13 has a first through hole 15 at one end part, in the opposed position to the bolt hole, a second through hole 16 in the inner direction, and a bolt inserted through the second through hole 16 and the through hole of the supporting metal fitting. The supporting member 17 is formed into roller shape with a ring groove 18 provided at the periphery, and fitted rotatably in the other end direction of the supporting rod 13.