An ultranarrow bandwidth Faraday atomic filter is realized based on cold Rb87 atoms. The atomic filter operates at 780 nm on the 52S1/2, F=2 to 52P3/2, F′=3 transition with a bandwidth of 7.1(8) MHz, which is approaching the natural linewidth of the transition. The peak transmission achieves 2.6(3)% by the multi-pass probe method. This atomic filter based on cold atoms may find potential applications in self-stabilizing lasers in the future.