A piezoelectric device includes an element substrate having a piezoelectric element and an electrically conductive pattern connected to the piezoelectric element, a supporting layer arranged within the periphery of the piezoelectric element, a cover extending so as to provide a groove inside the external periphery of the element substrate, the groove ranging over the entire external periphery of the element substrate by removing a portion of the cover and/or supporting layer inside the external periphery of the element substrate after the cover is arranged on the supporting layer, an insulating reinforcing material that entirely covers portions of the element substrate ranging from the cover to the periphery of a principal surface of the element substrate, and an electrically conductive member electrically connected to the electrically conductive pattern so as to pass through the cover and the reinforcing material.