There are no effective antiviral treatments for pigeon circovirus (PiCV); thus, rapid diagnosis is critical for effective control of the disease caused by this virus. The recent development of a novel LAMP technique that amplifies nucleic acids rapidly with high specificity and sensitivity under isothermal conditions has overcome some of the deficiencies of nucleic-acid-based diagnostic tests. We established a LAMP method for rapid detection of PiCV using two pairs of primers that were designed from PiCV and compared its sensitivity and specificity with that of PCR. Amplification by LAMP was optimal at 63 °C for 60 min. The detection limit was nearly 0.5 pg of PiCV DNA, making it ten times more sensitive than PCR. There was no cross-reaction with porcine circovirus type 2 (PCV2), pigeon Trichomonas gallinae, or pigeon herpesvirus (PHV) under the same conditions. The assay also successfully detected the pathogen DNA in the tissues of infected pigeons. This is the first report indicating that LAMP is a valuable, rapid method of detecting PiCV with high sensitivity and specificity.