Process for producing isocyanate compound

The present invention prevents the obstruction of a reactor tube in the production of an isocyanate compound. The present invention also produces an isocyanate compound at a high reaction rate in a high yield merely by pyrolysis. This process for producing an isocyanate compound includes: a step of feeding a carbamate compound together with a carrier gas into a hollow space where neither a solid catalyst nor a filler is present; and a step of conducting the pyrolysis of the carbamate compound in the hollow space. The value (N), which is calculated by dividing the capacity of the hollow space by the total amount of the carbamate compound and carrier gas fed per unit time, is 0.001 to 2.