  We construct the Dirichlet form associated with the dynamical $\Phi^4_3$
model obtained in [Hai14, CC13] and [MW16]. This Dirichlet form on cylinder
functions is identified as a classical gradient bilinear form. As a
consequence, this classical gradient bilinear form is closable and then by a
well-known result its closure is also a quasi-regular Dirichlet form, which
means that there exists another (Markov) diffusion process, which also admits
the $\Phi^4_3$ field measure as an invariant (even symmetrizing) measure.
