For 0.3T MRI instrument, a birdcage coil of low-pass type used for magnetic resonance imaging was designed. Its implementation is convenient because it requires one-half capacitors with respect to the high-pass style. Moreover at low-field, high near-electric field losses, which are the main disadvantage of the low-pass design, can be neglected. A detune circuit was designed and fixed on the rung of the birdcage coil to prevent the coil circuit from being destroyed by the high power induced when B1 field is transmitted. Detailed discussion of the design will be given in the presentation.