We report the superconducting characters in CeIrIn(5) studied by In-NQR measurements under pressure (P). In CeCoIn(5) and CeRhIn(5), the occurrence of superconductivity (SC) is related with the antiferrmagnetic spin fluctuations (AFM-SFs) originating from the antiferromagntic quantum-critical point (AFM-QCP). The high-T(c) SC (T(cmax) > 2 K) is realized in both compounds. However, in CeIrIn5 which is apart from the AFM-QCP, SC occurs even without AFM-SFs and the quite small value of T(cmax) (similar to 1 K) is observed around P = 3 GPa. The mechanism of SC in CeIrIn(5) may be different from that in CeCoIn(5) and CeRhIn(5).