PURPOSE: To obtain an aeration type optical disk cheaply without increasing the number of parts and number of processes of work by forming an air passage having the function of a filter in a body integrally with a spacer or a disk substrate.

CONSTITUTION: A rough face 4a is formed on one face of an inner peripheral spacer 4 out of spacers 4, 5. The roughness of the surface of the rough face 4a is determined by taking it into consideration of the necessary air conductance, the dust proofing effect and the accuracy of work, etc. An air gap is formed by adhering the inner peripheral spacer 4 and outer peripheral spacer 5 between disk substrates 1, 1. An air flowing hole 17 is formed in a part where an adhesives 8 that adheres the disk substrate 1 and the rough face 4a of the inner peripheral spacer 4 is not applied.