A thin-film transistor array device includes: a driving TFT including a first crystalline semiconductor film including crystal grains having a first average grain size; and a switching TFT including a second crystalline semiconductor film including crystal grains having a second average grain size that is smaller than the first average grain size. The first crystalline semiconductor film and the second crystalline semiconductor film are formed at the same time by irradiating a noncrystalline semiconductor film using a laser beam having a Gaussian light intensity distribution such that a temperature of the noncrystalline semiconductor film is within a range of 600° C. to 1100° C., and the first crystalline semiconductor film is formed such that the temperature of the noncrystalline semiconductor film is within a temperature range of 1100° C. to 1414° C. due to latent heat generated by the laser irradiation.