to 1 3 4 6 tetrathiapentalene 2 5 dione and allowed to undergo the ring opening reaction for about 10 minutes under a relatively low temperature condition of 30 u00b0 c or below especially at room temperature the process of the present invention for the production of tetrathiafulvalene derivatives and precursors thereof which include those of the present invention has been accomplished on the basis of such efforts according to the production process of the present invention as shown in the following reaction flow diagram one of the two rings of 1 3 4 6 tetrathiapentalene 2 5 dione 11 is selectively cleaved to obtain 1 3 dithiol 2 one 4 5 dithiolate dianion 12 which is subsequently allowed to react with a compound having a monovalent or divalent organic group that corresponds to r 1 and r 2 in formula 1 in this way a tetrathiafulvalene derivative precursor represented by formula 1 can be produced by a one pot and one step process without causing generation of hardly removable reaction by products because of this a tetrathiafulvalene derivative precursor can be produced in a high yield with a high purity in a short reaction time str9 a tetrathiafulvalene derivative can be produced by employing the above precursor producing step and a reaction step for the coupling of two molecules of the precursor thereby rendering possible production of the tetrathiafulvalene derivative in a high yield with a high purity in a short reaction time in addition the above production process can be carried out highly safely because it does not involve explosion causing.