To provide a tubular-member mounting device configured to mount a tubular member steadily to an insertion hole of a passage member.

A flange 11 includes a fluid passage 12 in which fuel flows, and an insertion hole 15 connecting the fluid passage 12 and an external air side. An axial one end of a tubular portion 23 of a housing 20 is inserted from the insertion hole 15 into the fluid passage 12. On a wall of an axial fluid passage side of a recessed groove 24 provided on the tubular portion 23, an inclined portion 25 is formed and inclined from a radial outside to a radial inside and from an axial direction fluid passage side to a circuit board accommodating portion 21 side. A clip 30 is fitted into the recessed groove 24 to press the inclined portion 25 in a radially inward direction. A clip holding portion 40 provided in the flange 11 holds the clip 30 on a radial outside of the insertion hole 15. When a force for moving the tubular portion 23 to the axial direction fluid passage side is applied to the inclined portion 25, a contact portion 26 provided on the axial fluid passage side of the housing 20 is pressed against the clip holding portion 40 by the pressing force of the clip 30.