  Interferometric observation of the CMB polarization can be expressed as a
linear sum of spherical harmonic coefficients $a_{\pm 2,lm}$ of the CMB
polarization. The linear weight for $a_{\pm 2,lm}$ depends on the observational
configuration such as antenna pointing, baseline orientation, and spherical
harmonic number $l,m$. Since an interferometer is sensitive over a finite range
of multipoles, $a_{\pm 2,lm}$ in the range can be determined by fitting $a_{\pm
2,lm}$ for visibilities of various observational configurations. The formalism
presented in this paper enables the determination of $a_{\pm 2,lm}$ directly
from spherical harmonic spaces without spherical harmonic transformation of
pixellized maps. The result of its application to a simulated observation is
presented with the formalism.
