We have developed an instrument to evaluate the infrared radiation (IRR) with regard to hazards (cataractogenesis). This instrument (IRR meter) measures approximately the total irradiance in the wavelength region of 770-1400 nm, referred to hereafter as effective irradiance (EI). The IRR meter indicates not only momentary EI but also detects, holds and indicates the maximum EI in any measuring time. This maximum is a most important factor in evaluating IRR varying with time. We describe the composition of the IRR meter and its important characteristics, which were investigated experimentally. It is concluded that the IRR meter is sufficiently applicable to measurements of IRR in the workplace in general, although some care may be required in individual measurements depending on measuring conditions or the characteristics of the IRR to be measured. Practically, with the IRR meter, we determined the levels of IRR from the shielded metal arc welding of mild steel and the metal active gas shielded arc welding of mild steel. The maximum EIs at 50 cm from the arc were 7.25 mW/cm2 and 1.71 mW/cm2, respectively.