In a previous study (2005 Comput. Phys. Commun.169, 139–143), we clarified the dependence of the phase structure on the hydrophilicity of an amphiphilic molecule by varying the interaction potential between the hydrophilic molecule and water ($a_{\rm AW}$) in a dissipative particle dynamics (DPD) simulation using the Jury model. In the present paper, we perform another DPD simulation using the previous model to investigate the dependence of the interaction potential between adjacent hydrophilic groups on the phase structure. By varying the coefficient of the interaction potential between adjacent hydrophilic groups $a_{\rm AA}$ ($a_{\rm AA}=15,25,40$ and 250) at a dimensionless temperature of $T=0.5$ and a concentration of amphiphilic molecules in water of $\phi=50$%, hexagonal ($a_{\rm AA}=14,25,40$) and micellar ($a_{\rm AA}=250$) phases were observed. In comparison with the previous results, the dependence of the A–B dimer's shape on $a_{\rm AA}$ was determined to be weaker than that on $a_{\rm AW}$. Therefore, it is concluded that the solvent water ${\rm W}$ plays an important role in aggregation of the A–B dimers.