Abstract: A monolithic crystal filter includes a crystal plate sealed airtight in a vessel. The vessel consists of a metal lid and a main body. The crystal plate is supported a predetermined distance from an insulating substrate. An input electrode and an output electrode are affixed to one surface of the crystal plate. A common electrode is affixed to the other surface of the crystal plate. The insulating substrate has a shield electrode thereon facing the input electrode and output electrode. The shield electrode is grounded to the metal lid of the vessel. An optimal distance between the shield electrode and the input electrode and the output electrode is disclosed for obtaining the best stopband attenuation level. An aluminum electrode island between the crystal plate and an electrode terminal develops an oxide coating which permits relaxation of stress and strain between the electrode island and its associated input and output electrodes to the resulting appropriate bonding strength therebetween.