Synchronization signal conversion device

[Problem] The purpose of the present invention is to enable the regeneration of a reference clock at a base station, even in an environment in which a GNSS signal or network signal cannot be received. [Solution] This synchronization signal conversion device is connected to a base station of a mobile communication system, and is characterized by comprising: a broadcast wave synchronization signal acquisition unit which receives a broadcast wave and acquires a synchronization signal from the broadcast wave; a timing adjustment unit which measures and maintains an offset value; a synchronization signal conversion unit which performs a conversion, on the basis of the synchronization signal, to a synchronization signal of a pseudo GNSS reception signal or a pseudo network reception signal in compliance with a GNSS signal or network signal; and a transmission unit which outputs the pseudo GNSS reception signal or pseudo network reception signal including the converted synchronization signal.