Abstract: A magnetic disc apparatus includes a casing for defining a sealed space, a magnetic disc disposed within the space, a spindle to which the magnetic disc is fixed, a motor for rotating the spindle, a flying head slider for writing and/or reading information in and/or from the magnetic disc and a carriage for translating the flying head slider. The magnetic disc apparatus incorporates an organic chemical compound capable of suppressing siloxane from being chemically changed to silicon oxide. The organic chemical compound contains at least one of monoalkyl-substituted benzene, dialkyl-substituted benzene, trialkyl-substituted benzene, fatty acid, fatty ester, alkyl ester of aromatic acid, thiazoles and phenols.