This study aimed to examine whether children working on infra-domain conservation tasks successfully involved cognitive inhibition process. Subjects were two groups of 11 years old children, and all of them passed standard Piaget conservation- of – weight tasks and conservation-of –liquid tasks. Experimental 1 observed a negative priming effect in Piaget-like conservation-of-weight tasks, which was 138.06ms. Experimental 2 also observed a negative priming effect in Piaget-like conservation-of-liquid tasks, which was 67.ms. These results showed that solving Piaget-like task in “infra-logic” domain did required a cognitive inhibition process.