We propose an interactive technique using onomatopoeia. Onomatopoeia are imitative words such as "Zig-zag" and "Tick-tock". Some Asian languages, especially Japanese and Korean, have many onomatopoeia words, which are frequently used in ordinary conversation, as well as in the written language. Almost all onomatopoeic words represent the texture of materials, the state of things and emotions. We consider that onomatopoeia allows users to effectively communicate sensory information to a computer. We developed a prototype painting system called Onomatopen, which enables a user to switch brushes and apply effects using onomatopoeia. For example, if the user draws a line while saying "Zig-zag Zig-zag...", a jagged line is drawn. As a result of our user test, we found that users can easily understand the usage and enjoy drawing with this application more than with conventional painting software.