To prevent generation of carbide at the time of starting pyrolysis equipment for converting plastic solution to product oil while continuously supplying the plastic solution into a pyrolysis vessel.

In method of starting pyrolysis equipment for converting plastic solution to product oil while continuously supplying the plastic solution into a pyrolysis vessel 7, a heat exchanging part 10 for heating the plastic solution is provided inside the above-mentioned pyrolysis vessel 7; and at the time of starting the pyrolysis equipment, the product oil is first supplied to the pyrolysis vessel 7, and heated; and the supply of the plastic solution to the pyrolysis vessel 7 is started after a state in which the product oil remaining in the pyrolysis vessel 7 generates convection or agitation is reached.