  Type Ia supernovae (SNe Ia) are believed to be a thermonuclear explosion of a
white dwarf, but the mass of their progenitors is still an open problem. In
near-Chandrasekhar-mass (near-M_Ch) models of SNe Ia, the central density
reaches >10^9 g cm^{-3}. The electron chemical potential becomes higher than
the Q-values of electron capture (EC) transitions between fp-shell nuclei, so a
portion of the available electrons is captured by iron group elements and thus
neutron-rich isotopes are formed. Since EC reaction rates are sensitive to the
density, the degree of neutronization is a key to distinguish near- and
sub-M_Ch models. In order to compare observations and theoretical models, an
accurate treatment of EC reactions is necessary. In previous theoretical works,
however, effects of electron screening on ECs are ignored. Screening lowers EC
rates and thus leads to a higher electron fraction. We implement electron
screening on ECs to calculate explosive SN Ia nucleosynthesis in a near-M_Ch
single degenerate model. It is found that some of neutron-rich nuclear
abundances, namely those of 46,48Ca, 50Ti, 54Cr, 58Fe, 64Ni and 67,70Zn,
decrease when screening effects on ECs are considered. Of these, 50Ti, 54Cr and
58Fe are particularly interesting because a significant portion of the solar
abundance of these nuclei is presumed to originate from SNe Ia. We conclude
that implementing the screening effect on ECs in modern SN Ia models is
desirable to precisely calculate abundances of neutron-rich nuclides.
