Three-dimensional (3D) III-V semiconductors including indium pnictides are widely used in optoelectronic devices, such as light-emitting diodes, laser diodes and photodetectors, in their bulk or thin-film geometries. On the other hand, two-dimensional (2D) atomic crystals such as graphene, phosphorene, and transition metal dichalcogenides are promising candidates for next generation optoelectronic technologies. Here, we designed a type of III-V indium pnictide 2D material that can be exfoliated and rebuilt from bulk wurtzite structures, which show benign stability and intriguing physical properties, including in-plane ferroelectricity/antiferroelectricity with low transition barriers (0.01-0.31 eV f.u.