A piezoelectric vibration element includes a piezoelectric substrate including a thin vibration region and a thick section integrated along three sides excluding one side of the vibration region, excitation electrodes respectively arranged on the front and rear surfaces of the vibration region, and lead electrodes. The thick section includes a first thick section and a second thick section arranged to be opposed to each other across the vibration region and a third thick section connected between proximal ends of the first and second thick sections. The second thick section includes an inclined section connected to the one side of the vibration region, a second thick section main body connected to the other side of the inclined section, and at least one slit for stress relaxation.