Provided is a gas separation membrane 10 including a separation layer 1 which comprises a block copolymer having at least a first segment and a second segment, in which the separation layer 1 has a phase separation structure that has at least a first structure 11 derived from the first segment and a spherical second structure 12 derived from the second segment. The gas separation membrane in which the spherical second structure satisfies Formula 1, the first structure and the spherical second structure satisfy the following Formula 2, and the first structure 11 has a structure that is continuous in the thickness direction over the entire thickness of the separation layer 1 has high gas permeability and high gas separation selectivity. Also provided is a gas separation membrane module. R/L