  We study the prospect of dark matter (DM) searches in the monojet channel at
future $pp$ colliders with center-of-mass energies of 33, 50, and 100~TeV. We
consider a class of simplified models in which a vector boson connecting DM
particles to quarks is introduced. Comparing with studies in the effective
field theory, the present framework gives more reasonable production rates and
kinematics of the DM signatures. We estimate the sensitivities of future
colliders with an integrated luminosity of 3 $ab^{-1}$ to the DM-induced
monojet signature and show the parameter space that can be explored. The
constraints from direct and indirect DM detection experiments are compared with
the future collider sensitivities. We find that the future collider detection
will be much more sensitive than the indirect detection for the vector
interaction, and have better sensitivities than those of the direct detection
by several orders of magnitude for the axial vector interaction.
