  We study contributions of single scalar or vector leptoquark (LQ) to
loop-induced Higgs processes, gluon fusion production ($g g \to h$) and $h \to
\gamma \gamma$ decay, by analyzing the current Higgs data from the LHC Run I
and II. Scalar LQ is studied in a model independent way, while the vector LQ
$U_1(\mathbf{3},\mathbf{1},2/3)$ is discussed in the '4321' model. Constraints
on the interactions of LQ and Higgs boson are obtained. We provide a method to
determine vacuum expectation values $\upsilon_3$ and $\upsilon_1$ of the new
scalar fields $\Omega_3$ and $\Omega_1$ in the '4321' model via the combination
of Higgs data and measurements of $R_{D^{(*)}}$ and $R_{K^{(*)}}$.
