PURPOSE: To provide a fan filter device for a clean room generating a low noise sound by a method wherein a shielding plate having a sound muffling material stuck thereto is fixed within a chamber to cause the distribution of air blowing speed is made uniform.

CONSTITUTION: A blower 2 comprised of an inlet cone 21 and a runner 22 rotated in a horizontal direction is fixed to a central part of a top plate within a chamber 1 having its lower part opened. In a fan filter device for a clean room having a filter 3 fixed to a lower opening, a first shielding plate 4 having a sound muffling material 44 with a flange 42 inclined to enclose the runner 22 is fixed in a space between a blower 2 and a filter 3, and a second shielding plate 5 having sound muffling material 44 kept in a horizontal direction or inclined with a specified space with a flange of the first shielding plate 4 is fixed to a side plate of a chamber. With such an arrangement as above, it is possible to make a uniform distribution of air speed of blown air, increase a sound absorbing effect and reduce a generated noise.