the invention provides a signal transmission apparatus and a signal recording apparatus by which , while a rotary transformer is used , a wide bandwidth and a high transfer rate can be used without a significant increase of the cost or a bad influence on signal recording . a rotary transformer is interposed between a transmission side circuit and a reception side circuit . a passive element circuit including an inductance element is connected to an input stage , that is , the stator side , of the rotary transformer in parallel to the rotary transformer . the passive element circuit has an inductance value set equal to or lower than an equivalent inductance value when the circuit of the rotary transformer side is viewed from the transmission side circuit to achieve impedance matching .