Electric power transmission system and antenna

An electric power transmission system includes: a transmitting-side system that includes switching elements (SW1 and SW2) that convert a direct-current voltage to an alternating-current voltage and that output the alternating-current voltage and a transmitting-side magnetic resonance antenna unit (120) that has a first inductor (121) and a first capacitor (122) directly coupled to each other and to which the output alternating-current voltage is input; and a receiving-side system that includes a second inductor (221) and a second capacitor (222) directly coupled to each other and that resonates with the transmitting-side magnetic resonance antenna unit (120) via electromagnetic field to thereby receive electric energy output from the transmitting-side magnetic resonance antenna unit (120).