Quantum infrared spectroscopy (QIRS), which harnesses the quantum interference between entangled visible and infrared photon-pair-generation processes in a nonlinear quantum interferometer, has attracted considerable attention for realizing infrared spectroscopy with high-performance visible detectors and light sources. However, a shortcoming of QIRS is its vulnerability to wave-front distortion caused by the sample structure, which can degrade the quantum interference. To address this problem, we propose employing the attenuated total-reflection (ATR) method, which utilizes close contact between the sample and a prism. The ATR method is one of the most utilized methods in infrared spectroscopy since it can be used to measure various types of materials, such as liquid, film, and powder samples, and is therefore useful for real-world applications. Here, we report wavelength-tunable ATR-QIRS measurements. We constructed a Michelson-type nonlinear quantum interferometer with a
CaF2 prism, and measured the absorption of water OH-stretching (approximately $3\phantom{\rule{0.2em}{0ex}}\text{\ensuremath{\mu}}\mathrm{m}$). The transmission spectrum obtained by our ATR-QIRS system shows good agreement with a numerically calculated transmission spectrum using the Fresnel equation.