The absolute photoabsorption cross sections sigma(a) and photoionization quantum yields eta of Cr(CO)(6), Mo(CO)(6), and W(CO)(6) are measured in the wavelength range of similar to 300-1600 Angstrom. We have also estimated the photoionization cross sections sigma(i) and the neutral photodissociation cross sections sigma(d) from sigma(a) and eta. Main absorption features are tentatively assigned with the help of the MO diagram and the photoeIectron spectroscopic data of M(CO)6(M=Cr,Mo,W). Large optical oscillator strength distributions and neutral photodissociation cross sections are obtained at the photon energies far beyond the first ionization potential. Our studies revealed the valence excitation nature of tile superexcited states in the extreme ultraviolet region. It is suggested that the neutral photodissociation in this region shares a similarity with that in the UV region below the first ionization potential because they both involve a repulsive ejection of the first CO ligand.