A pyroelectric element includes a pyroelectric substrate being a substrate of lithium tantalate single crystal having an X-axis, a Y-axis, and a Z-axis as crystal axes; front-side electrodes disposed on a front side of the pyroelectric substrate; and back-side electrodes paired with the front-side electrodes, respectively. The pyroelectric substrate is a Y-offcut plate obtained by cutting the lithium tantalate single crystal at an angle turned by a cut angle θ from the Y-axis toward the Z-axis about the X-axis that coincides with a direction along the electrode plane, and the cut angle θ is 30° to 60° or 120° to 150°. The pyroelectric substrate is preferably 10 μm or less in thickness, and is more preferably 5 μm to 10 μm in thickness.