In a chiral quark model of the Nambu-Jona-Lasinio type with 't Hooft intera
ction, we calculate the mass spectra of pseudoscalar and scaler masons. We
obtain a satisfactory result for the pseudoscalar masons. The 't Hooft inte
raction increases, to some extent, the scalar-meson masses, but this increa
se is not sufficient to explain the entire scalar-mass spectrum. The situat
ion could be improved for the sigma and f(0) mesons through mixing with the
glueball state. In order to describe the masses of a(0) and K-0* mesons, i
t is necessary to invoke other models. The strong-decay widths of the scala
r mesons are described.