An illuminating unit with a compact design capable of improving collimating characteristics of beams emitted from a plurality of light sources positioned at different locations, and a projection-type image display apparatus employing the illuminating unit. The illuminating unit includes a base, a plurality of light sources to emit beams of different wavelength bands, and at least one color filter with a predetermined curvature to reflect one or more beams of predetermined wavelengths from among the beams emitted by the plurality of light sources such that the reflected one or more beams propagate in a first direction and to pass one or more remaining beams of other wavelength bands. The projection-type image display apparatus includes the illuminating unit, an optical integrator, an image-forming system, a beam splitter, and a projection lens.