The quantization of the forced harmonic oscillator is studied with the quantum variable (
x,
v∧), with the commutation relation
, and using a Schr
ödinger’s like equation on these variable, and associating a linear operator to a constant of motion
K (
x, v, t) of the classical system, The comparison with the quantization in the space (
x, p) is done with the usual Schr
ödinger’s equation for the Hamiltonian
H(x, p, t), and with the commutation relation
. It is found that for the non-resonant case, both forms of quantization bring about the same result. However, for the resonant case, both forms of quantization are different, and the probability for the system to be in the exited state for the (
x, v∧) quantization has fewer oscillations than the (
x, p∧) quantization, the average energy of the system is higher in (
x, p∧) quantization than on the (
x, v∧) quantization, and the Boltzmann-Shannon entropy on the (
x, p∧) quantization is higher than on the (
x, v∧) quantization.