Optical filter and its applications, and porphyrin compound used in optical filter

An optical filter of the present invention contains at least one tetra-acenaphthoporphyrin compound. The tetra-acenaphthoporphyrin compound has preferably its absorption maximum in a wavelength range of from 530 to 570 nm and a ratio of an absorption coefficient at 550 nm to an absorption coefficient at 525 nm of not less than 1.2. Also, a percentage of light transmittance at 550 nm to light transmittance at 525 nm is preferably not more than 85%. According to the present invention, it is possible to provide the optical filter which can eliminate an unnecessary light mainly existing in a wavelength of from 520 to 700 nm and is excellent in durability. A display unit using the optical filter of the present invention can improve contrast in a bright place, and improve color purity of luminescent color.