The dependence of the lasing characteristics of a novel ridge structure with optical antiguiding layers for horizontal transverse modes on step positions in the guiding lasers is theoretically investigated. It is found that steps in both the upper guiding layer, which is adjacent to the p-cladding layer, and the lower guiding layer, which is adjacent to the n-cladding layer, increase kink level and the contribution of the steps in the upper guiding layer is higher than that of the steps in the lower guiding layer. It is also revealed that steps in the upper guiding layer decrease threshold current and those in the lower guiding layer slightly increase threshold current.