Continuous-wave (CW) laser lateral crystallized silicon (Si) thin films were investigated. CW laser with a wavelength λ of 532 nm was applied to crystallization. In the CW laser lateral crystallization (CLC), a gradual temperature slope in Si thin films was farmed and one-dimensionally long grains with a typical length of 20 μm were achieved. The most dominant grain growth direction was <110> direction. σ3, 9, and 11 boundaries were mainly observed between adjacent grains. It was found that crystallization was performed to form stable grain boundaries. It was also clarified that CLC poly-Si thin films have large tensile strain corresponding to 0.6% of single crystalline Si lattice in in-plane direction. This strain was induced by the difference in thermal expansion coefficients between Si thin films and the buffer SiO2 films.