The present invention provides a wavelength selective optical focusing device using the cladding-etching of an optical fiber and an optical module using the same. The wavelength selective optical focusing device includes a core for transmitting an optical signal therethrough; and a cladding layer surrounding the core and having a plurality of grooves formed in the outer circumferential surface thereof such that the grooves are changed at a designated rate, wherein an optical signal having a designated wavelength guided by the core is focused to the outside of the cladding layer by the grooves.