Various InGaN/GaN pn‐junction nanocolumn arrays arranged in a triangle lattice are grown on the same substrate while changing the nanocolumn diameters (Dn‐GaN) of the underlying n‐side GaN region under the lattice constant (L) of 340 nm. The nanocolumn diameter increases during the growth of the active InGaN and p‐side GaN regions. The periodic arrangement of nanocolumns leads to a photonic crystal effect. Redshift of the band edge wavelength, from 573 to 629 nm, is observed as Dn‐GaN increases from 159 to 282 nm. This phenomenon can be explained by the fact that the larger filling factor increases the effective refractive index of the nanocolumn system, resulting in a redshift of the band edge. The light diffraction at the photonic band edge induces the directional radiation beam from the surface of the nanocolumn system. Using the nanocolumn array with Dn‐GaN = 260 nm, the red‐emitting (λ = 637 nm) nanocolumn light‐emitting diodes with the radiation angle of ±30° are demonstrated.