Culm length (CL) is composed of different elongated internode lengths (EILs) and is closely correlated to the lodging resistance in rice (Oryza sativa L.). The objective of this study was to identify quantitative trait loci (QTLs) stably associated with CL and the first to fourth EIL from panicle base, which were abbreviated as FIL (first), SIL (second), TIL (third), and FOIL (fourth) in japonica rice, respectively. Association mapping was conducted using the genotypes determined by 154 simple sequence repeat markers and the phenotypes in 2010, 2011, and 2015 of 331 japonica rice accessions. The study mapped 6, 5, 15, 2, and 2 QTLs tagged by 22 markers on eight chromosomes and stably associated with CL, FIL, SIL, TIL, and FOIL, respectively. Five QTLs, qCL‐6‐2, qFIL‐6‐5, qSIL‐6‐2, qTIL‐6‐3, and qFOIL‐7‐5, explained the largest phenotypic variance of CL, FIL, SIL, TIL, and FOIL, respectively. RM1340, RM1374, RM281, RM233, and RM225 were stably and specifically associated with CL, FIL, SIL, TIL, and FOIL, respectively. Forty‐three effective alleles were identified. Four and three donors with negative and positive alleles were recommended. There was a highly significant phenotypic difference between accessions with or without effective alleles. These QTLs, associated markers, effective alleles, and their donors could be used to improve CL and specific EIL in japonica rice.