Electrical current induced joule heating method was applied to crystallization of 50 nm-thick amorphous silicon films formed on glass substrates. Voltages were applied to silicon films connected with a capacitance in parallel. Irradiation with 5 ns-pulsed-laser melted films partially and caused electrical current induced joule heating because of reduction of electrical resistance. Lateral grain growth with 12.6 µm was realized using the tapered-shaped-electrodes to apply voltages to silicon films with a capacitance of 0.33 µF. For 2.6×10 17 cm−3 phosphorus-doped films, analysis of temperature change in the electrical conductivity gave that defect states at grain boundaries was low of ∼1017 cm−3.