During membrane depolarization associated with skeletal excitation-contraction (EC) coupling, dihydropyridine receptor [DHPR, a L-type $Ca^{2+}$ channel in the transverse (t)-tubule membrane] undergoes conformational changes that are transmitted to ryanodine receptor 1 [RyR1, an internal $Ca^{2+}$-release channel in the sarcoplasmic reticulum (SR) membrane] causing $Ca^{2+}$ release from the SR. Canonical-type transient receptor potential cation channel 3 (TRPC3), an extracellular $Ca^{2+}$-entry channel in the t-tubule and plasma membrane, is required for full-gain of skeletal EC coupling. To examine additional role(s) for TRPC3 in skeletal muscle other than mediation of EC coupling, in the present study, we created a stable myoblast line with reduced TRPC3 expression and without ${alpha}1_SDHPR$ (MDG/TRPC3 KD myoblast) by knock-down of TRPC3 in ${alpha}1_SDHPR$-null muscular dysgenic (MDG) myoblasts using retrovirus-delivered small interference RNAs in order to eliminate any DHPR-associated EC coupling-related events. Unlike wild-type or ${alpha}1_SDHPR$-null MDG myoblasts, MDG/TRPC3 KD myoblasts exhibited dramatic changes in cellular morphology (e.g., unusual expansion of both cell volume and the plasma membrane, and multi-nuclei) and failed to differentiate into myotubes possibly due to increased $Ca^{2+}$ content in the SR. These results suggest that TRPC3 plays an important role in the maintenance of skeletal muscle myoblasts and myotubes.