A vibrating device includes a drive unit configured to drive a vibrating member to produce vibration Z (x, y) at a dust-screening member, the vibration being expressed as follows: Z(x,y)=Wmn(x,y)·cos(γ)+Wnm(x,y)·sin(γ) where Z (x, y) is vibration at a given point P (x, y) on the dust-screening member, m and n are positive integers including 0, indicating the order of natural vibration corresponding to a vibrational mode, W mn ⁡ ( x , y ) = sin ⁡ ( n ⁢ ⁢ π · x + π 2 ) · sin ⁡ ( m ⁢ ⁢ π · y + π 2 ) , ⁢ W n ⁢ ⁢ m ⁡ ( x , y ) = sin ⁡ ( m ⁢ ⁢ π · x + π 2 ) · sin ⁡ ( n ⁢ ⁢ π · y + π 2 ) , and γ is +π/4 or ranges from −π/8 to −π/4. A ratio between a first bending rigidity along the X-axis of at least the dust-screening member and vibrating member in the section orthogonal to the X-axis at the intersection of the X- and Y-axes, to a second bending rigidity along the Y-axis of at least the dust-screening member and vibrating member in the section orthogonal to the Y-axis at the intersection is 0.4 or more, but less than 1.0.