A heater block according to the present invention comprises a light-emitting lamp; a concave reflecting member that is placed opposite the lamp and has a concave reflecting surface at one surface faced with the lamp; a lens module that is inserted into the concave reflecting member and has at least one lens; and a flat reflecting member that is placed opposite the lens module. According to embodiments of the present invention, light emitted from the lamp is reflected by the concave reflecting member. Then, light and heat are collected from the reflected light by the flat reflecting member and the lens module and are irradiated on a substrate. That is, light having energy greater than a conventional manner is irradiated on the substrate to enhance the instant heating temperature and temperature increasing rate of substrate and to increase a heat-focusing area. Therefore, it has an advantage that the productivity of semiconductor or display device manufacture that requires a rapid thermal process is improved.