Titanium alloys are widely used as mechanical components, since they have superior properties such as high strength-to-weight ratio. They are regarded as difficult-to-cut materials. Their low thermal conductivity increases the temperature near the cutting edge, which causes excessive tool wear during cutting. Recently, many studies on cryogenic machining have been conducted. Cryogenic machining has emerged as an environmentally friendly alternative to traditional emulsion coolants. In this study, the rake face temperatures of cutting tool in the turning of titanium alloy under dry, soluble coolant, cryogenic carbon dioxide coolant and liquid nitrogen coolant conditions were measured to clarify the effect of coolant on cutting temperature. Turning tests were performed using a precision lathe. Tool insert was made by a translucent alumina. A small hole was drilled into the tool insert. An infrared radiation pyrometer with an optical fiber was used. The optical fiber was inserted into the hole. During chip formation, the infrared rays, radiated from the tool-chip interface and transmitted through the cutting tool, were accepted and transmitted by the optical fiber. The effects of cryogenic coolant on the rake face temperature were investigated. The rake face temperatures under carbon dioxide cooling and liquid nitrogen cooling were approximately 60 °C and 90 °C lower than that in dry cutting, respectively.