As theoretical predictions as experiments allow expecting the photon presence in cosmic rays of extremely high energy (EHE). The task of γ-shower separation from others appears. The influences of two effects are important in the EHE energy region: the Landau-Pomeranchuk-Migdal effect and the interaction of EHE photons and electrons with the geomagnetic field. We carry out calculations of electromagnetic cascades in the atmosphere for EHE γ-rays with taking into account both these effects. The photon component of such showers is investigated by us.