Context : We report the detection of unidentified infrared ( UIR ) bands in a filamentary structure associated with H \alpha emission in the starburst dwarf galaxy NGC1569 based on imaging and spectroscopic observations of the AKARI satellite . Aims : We investigate the processing and destruction of the UIR band carriers in an outflow from NGC1569 . Methods : We performed observations of NGC1569 for 6 infrared bands ( 3.2 , 4.1 , 7 , 11 , 15 , and 24 \mu m ) with the Infrared Camera ( IRC ) onboard AKARI . Near- to mid-infrared ( 2–13 \mu m ) spectroscopy of a H \alpha filament was also carried out with the IRC . Results : The extended structure associated with a H \alpha filament appears bright at 7 \mu m. Since the IRC 7 \mu m band ( S7 ) efficiently traces the 6.2 and 7.7 \mu m UIR band emission , the IRC imaging observations suggest that the filament is bright at the UIR band emission . Follow-up spectroscopic observations with the IRC confirm the presence of 6.2 , 7.7 , and 11.3 \mu m emission in the filament . The filament spectrum exhibits strong 11.3 \mu m UIR band emission relative to the 7.7 \mu m band compared to the galaxy disk observed with the Infrared Spectrograph on Spitzer . The near-infrared spectrum also suggests the presence of excess continuum emission in 2.5–5 \mu m in the filament . Conclusions : The presence of the UIR bands associated with a H \alpha filament is found by AKARI /IRC observations . The H \alpha filament is thought to have been formed by the galactic outflow originating from the star-formation activity in the disk of NGC1569 . The destruction timescale of the UIR band carriers in the outflow is estimated to be much shorter ( \sim 1.3 \times 10 ^ { 3 } yr ) than the timescale of the outflow ( \sim 5.3 Myr ) . Thus it is unlikely that the band carriers survive the outflow environment . Alternatively , we suggest that the band carriers in the filaments may be produced by the fragmentation of large carbonaceous grains in shocks , which produces the H \alpha emission . The NIR excess continuum emission can not be accounted for by free-free emission alone and a hot dust contribution may be needed , although the free-free emission intensity estimated from H i recombination lines has a large uncertainty .