We present the optical photometry and spectroscopy of an atypical Type IIP SN, SN 2015ba, in the galaxy IC 1029, from about a week after the explosion to ~272 days. The mid-plateau luminosity of SN 2015ba is -17 mag in V band, which categorizes it under normal luminosity SNe IIP. However, this event continues in its plateau phase for a longer time (~123 days) and exhibits a larger and steeper decline from the plateau to the radioactive tail (~3 mag in 20 days) than most SNe IIP. The longer plateau phase indicates that the progenitor has undergone minimal mass loss prior to explosion. We also estimate the explosion parameters from hydrodynamical modelling, such as the 56Ni mass (0.032 Msun), the kinetic energy of explosion (~1.7 foe) and the ejecta mass (~22 Msun). The progenitor properties ascertained from the modelling are the initial radius of the progenitor star (~500 Rsun) and the mass of the progenitor prior to explosion (~24 Msun), which implies that the most probable progenitor of SN 2015ba is a massive red supergiant star.