RFID TAG AND RFID SYSTEM

To provide an RFID tag (100) capable of performing communications stably regardless of the RFID tag being attached to a metallic member or being attached to a non-metallic member. The RFID tag (100) includes a base part (101) made of dielectric material and having plate-like shape, a loop antenna (140, 240) around the base part (101) including a first antenna element (110) and a second element (120), and a loop-length shorter than a wavelength of a resonant frequency, and an IC chip (130) placed at a first surface side of the base part (101). The IC chip is connected between a first terminal (113) disposed on a first end of the first antenna element (110) and a second terminal (123A) disposed on a first end of the second antenna element (120). The loop antenna (140, 240) includes an overlapping part (160) at a second surface side of the base part (101), and a capacitance of the overlapping part is adjusted such that a difference between an imaginary component of a first synthetic impedance and an imaginary component of a second synthetic impedance is less than or equal to a predetermined value.