Laser generation of ultrasonic waves is attracting increasing attention as a means of non-contact and nondestructive ultrasonic testing. Laser-generated ultrasound has broad-band characteristics, however, which makes the resulting elastic wave field very complex, especially for guided waves in a thin structure due to their dispersive nature and multiple-mode existence. Numerical simulations are highly effective in clarifying the complex mechanism of ultrasonic guided wave generation and propagation in various laser irradiation conditions. Analysis of laser-generated ultrasound requires accurate modeling of laser-induced heat generation and the accompanying thermal expansion. Furthermore, the propagation of elastic waves in solid media is generally coupled to heat conduction through thermoelasticity. Therefore, the analysis should be performed in the framework of dynamic, coupled thermoelasticity. Among various techniques for numerical simulations of elastic wave generation/propagation, the elastodynamic finite integration technique (EFIT), proposed by Fellinger and Langenberg (1990), has been applied to various problems related to ultrasonics, e.g., Fellinger et al. (1995), Nakahata et al. (2009). EFIT is particularly advantageous in setting boundary conditions and defining distribution of material properties. In the present study, EFIT is extended to dynamic, coupled thermoelastic problems in order to analyze Lamb waves generated in a thin plate by multiple line heat sources, which models laser irradiation through a mask with line-arrayed slits.