It is an object of the present invention to solve difficulty in production and to provide a process to obtain fluorinated sulfonyl fluoride compound having various molecular structures efficiently at a low cost.That is, the present invention provides a process which comprises reacting (FSO2—)nRA(-E-RB)m (1F) with fluorine in a liquid phase to form (FSO2—)nRAF(-EF-RBF)m (2), and decomposing this compound to obtain (FSO2—)nRAF(-EF1)m (3), provided that RA is a (n+m) valent organic group having at least two carbon atoms, RAF is a group having RA fluorinated, or the like, each of RB and RBF is a fluorinated monovalent organic group, or the like, E is —COOCH2— or the like, EF is —COOCF2— or the like, EF1 is —COF or the like, n is an integer of at least 2, and m is an integer of at least 1.