An antenna module includes a dielectric substrate, multiple patch antennas provided at a first main surface side of the dielectric substrate, and an RFIC mounted at a second main surface side of the dielectric substrate. The multiple patch antennas include multiple sets of antenna groups each composed of the multiple patch antennas periodically arranged at a pitch Px in the X-axis direction, which is one of a polarization direction and a direction perpendicular to the polarization direction. The multiple sets of antenna groups are periodically arranged at a pitch Py in the Y-axis direction, which is the other of the polarization direction and the direction perpendicular to the polarization direction, and each of the multiple sets of antenna groups is arranged so as to be shifted from another antenna group adjacent in the second direction by an offset distance Dx in the first direction.