We have obtained a transfer function satisfying the two necessary geophysical constraints, based on the formulation of Sasao, Okubo, & Saitō. We have also developed a realistic model of the free core nutation (FCN) by taking into account the recent discovery of FCN excitations. Using these, we construct a new theory of the forced nutation of the nonrigid Earth. First we adopt RDAN97 as the rigid-Earth nutation theory. Next, this is convolved numerically with the transfer function in the time domain. Then the free parameters of the transfer function are adjusted by fitting the convolved nutation theory to the latest VLBI observations of the nutation for the period 1979–2000, after subtracting the geodesic nutation and the FCN model. Through examination of the dependence of the residuals on the number of nutation terms, we truncate the series to only 194 terms. The resulting weighted rms of the residuals for the new nutation series is 0.280 mas, which is significantly smaller than 0.296 mas, that of the best empirical model, IERS 1996, which contains 381 terms. We estimate the oscillatory period of the FCN term to be -431.0(6) sidereal days and its Q-value to be 1.53(10) × 104. We estimate the correction to the celestial ephemeris pole offsets at J2000.0 to be -0042888(10) in longitude and -0005171(10) in obliquity. Further, the corrections to the precession constants are determined to be -029856(30) per century in longitude and -002408(16) per century in obliquity. As for the geophysical parameters, we estimate the dynamical ellipticity of the whole Earth to be 0.003273972(3). We also determine the Love number of the solid Earth to be 0.2788(11) with a phase lag of 713(23).