We propose a solution to the supersymmetry (SUSY) $\mu$ problem within the framework of modular flavor symmetry. The explicit $\mu$ term is prohibited by modular symmetry, and an effective $\mu$ term is regenerated following the stabilization of the modulus field. We examine the stabilization mechanism of a single modulus field with the presence of SUSY breaking contributions described by the nonlinear SUSY realization scheme involving a nilpotent Goldstino ${\mathbf{X}}_{nl}$ superfield. A natural small ${\mu }_{\mathrm{eff}}$, significantly smaller than the SUSY scale, can result from either the expansion of typical modular forms using a small deviation parameter near the fixed point $\omega$, or from the combined effects of suppression by powers of $q^{1/24}$ [or $(2\Im \tau {)}^{-1}$] along with the asymptotic suppression behavior of typical modular forms away from the fixed point $i\infty$, taking the form of appropriate power of the tiny deviation parameter. A natural small ${\mu }_{\mathrm{eff}}$ can also be achieved by a weightonlike mechanism for $H_u{H}_d$ bilinear.

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• Naturalness
• Flavor symmetries
• Supersymmetry