A power supply device includes: a power supply unit configured to output the power of a mainframe; and a power transmission cable configured to supply the power output from the power supply unit to the mainframe via a connector; with the power transmission cable including a mainframe side high-frequency cutoff portion disposed between the power supply terminal of the connector, a power supply unit side high-frequency cutoff portion, which is disposed on the power supply unit side at a predetermined length from the connector, configured to restrict the length of a portion serving as an antenna, a first transmission line used for power supply to the mainframe via the mainframe side high-frequency cutoff portion, and a second transmission line to be connected to a tuner of the mainframe via the connector.