A magnetosonic shock wave propagating obliquely to a magnetic field is studied by theory and simulation, with particular attention to the resonant ion acceleration (thevp×Bacceleration) by the shock. Theoretical analysis based on a two‐fluid model shows that, in the laminar shock, the electric field strength in the direction normal to the wave is about (mi/me)1/2times larger for the quasiperpendicular shock than that for the quasiparallel shock, which is a reflection of the fact that the width of the quasiperpendicular shock is much smaller than that of the quasiparallel shock. Time evolution of a totally self‐consistent magnetosonic shock wave is studied by using a 2 1/2 ‐dimensional fully relativistic, fully electromagnetic particle simulation with full ion and electron dynamics. Even the low Mach number shock wave can significantly accelerate some ions by thevp×Bacceleration. The resonant ion acceleration occurs more strongly in the quasiperpendicular shock, because the magnitude of this acceleration is proportional to the electric field strength.