To quickly and properly dry print ink without using hot air.

This ink drying device is used for drying print ink i transferred to a belt-shaped printed base material P. This ink drying device includes a guide roller 35 supporting the printed base material P transferrably in the longitudinal direction, an infrared ray heater unit 36 having a plurality of heating elements 36 radiating near infrared ray of wavelength of 0.78-2.5 m, and movable between a first position close to a printed face Pa of the base material P and a second position separating from the printed face Pa, a heating quantity adjusting section 37 for adjusting the heating quantity of each heating element 36b, and a fluid pressure cylinder for moving the infrared ray heater unit 36 from the first position to the second position when the transferring of the printed board in the longitudinal direction is stopped. The base material P and the infrared ray heater unit 36 are relatively moved at a constant speed in a state of keeping a constant distance between the printed face Pa and the infrared ray heater unit 36, while irradiating the printed face Pa of the base material P with near infrared ray.