The 1/3 octave real‐time analyzer is used especially for research of evaluation or reduction of environmental noise and vibration. Since it has been very expensive, large, and heavy, and dependent on external power sources, users were limited and the field operation was difficult. We have newly developed fully portable 1/3 octave real‐time analyzer Model SA‐24, which has 3.5‐in. CRT display, measures 29(W) × 10(H) × 36(D) cm, weighs 8.5 kg and operates with internal rechargeable battery (about 4 hours continuous operation), AC line and external DC. The price has become as less expensive as 1/3 of other equivalent models. Model SA‐24 has plug‐in filters of multi‐channel covering 31.5 Hz through 8 kHz for 1/3 or 1/1 octave band analysis and 1 Hz through 250 Hz for 1/3 octave band analysis. The band level is detected by RMS detector at crest factor 3 (± 0.5 dB), and the averaging time constant can be selected between 0.1 s and 10 s. The dynamic range of level detection and display is over 40 dB, and instantaneous and maximum level hold can be made. The spectrum pattern can be read out to level recorder or to other instuments.