A power generation unit comprising: a flexible vibration board; a piezoelectric element fixed on at least one of the surfaces of the vibration board, the piezoelectric element being formed in a plate body shape; a deformation promoting unit that promotes deformation of the piezoelectric element caused by vibration of the vibration board, the deformation promoting unit comprising a fixing board and a weight; and a restricting unit that restricts a vibration range of the vibration board, the restricting unit being formed in a plate body shape or a cubic shape, wherein the fixing board is arranged on a side of the piezoelectric element and at a position where the fixing board sandwiches the piezoelectric element together with the vibration board, one end of the vibration board, one end of the fixing board, and one end of the restricting unit are fixed on an installation surface, the weight is fixed to a free end of the vibration board, the restricting unit is arranged on the side of the fixing board such that the vibration board is allowed to deform, the vibration board comes into contact with the restricting unit immediately before the vibration board excessively vibrates to such a degree that the vibration board plastically deforms, and the weight does not come into contact with the restricting unit, and one edge of the fixing board that is opposite to the one end fixed on the installation surface always cuts across the side surface of the piezoelectric element so that said one edge of the fixing board functions as a fulcrum when the piezoelectric element deforms. a flexible vibration board; a piezoelectric element fixed on at least one of the surfaces of the vibration board, the piezoelectric element being formed in a plate body shape; a deformation promoting unit that promotes deformation of the piezoelectric element caused by vibration of the vibration board, the deformation promoting unit comprising a fixing board and a weight; and a restricting unit that restricts a vibration range of the vibration board, the restricting unit being formed in a plate body shape or a cubic shape, wherein the fixing board is arranged on a side of the piezoelectric element and at a position where the fixing board sandwiches the piezoelectric element together with the vibration board, one end of the vibration board, one end of the fixing board, and one end of the restricting unit are fixed on an installation surface, the weight is fixed to a free end of the vibration board, the restricting unit is arranged on the side of the fixing board such that the vibration board is allowed to deform, the vibration board comes into contact with the restricting unit immediately before the vibration board excessively vibrates to such a degree that the vibration board plastically deforms, and the weight does not come into contact with the restricting unit, and one edge of the fixing board that is opposite to the one end fixed on the installation surface always cuts across the side surface of the piezoelectric element so that said one edge of the fixing board functions as a fulcrum when the piezoelectric element deforms. the restricting unit being formed in a plate body shape or a cubic shape, wherein the fixing board is arranged on a side of the piezoelectric element and at a position where the fixing board sandwiches the piezoelectric element together with the vibration board, one end of the vibration board, one end of the fixing board, and one end of the restricting unit are fixed on an installation surface, the weight is fixed to a free end of the vibration board, the restricting unit is arranged on the side of the fixing board such that the vibration board is allowed to deform, the vibration board comes into contact with the restricting unit immediately before the vibration board excessively vibrates to such a degree that the vibration board plastically deforms, and the weight does not come into contact with the restricting unit, and one edge of the fixing board that is opposite to the one end fixed on the installation surface always cuts across the side surface of the piezoelectric element so that said one edge of the fixing board functions as a fulcrum when the piezoelectric element deforms.