An endo-arabinanase (BLABNase) gene from Bacillus licheniformis DSM13 was cloned and expressed in Escherichia coli, and the biochemical properties of its encoded enzyme were characterized. The BLABNase gene consists of a single open reading frame of 987 nucleotides that encodes 328 amino acids with a predicted molecular mass of about 36 kDa. BLABNase exhibited the highest activity against debranched ${alpha}$-(1,5)-arabinan in 50 mM sodium acetate buffer (pH 6.0) at $55^{circ}C$. Enzymatic characterization revealed that BLABNase hydrolyzes debranched or linear arabinans with a much higher activity than branched arabinan from sugar beet. Enzymatic hydrolysis pattern analyses demonstrated BLABNase to be a typical endo-(1,5)-${alpha}$-$small{L}$-arabinanase (EC 3.2.1.99) that randomly cleaves the internal ${alpha}$-(1,5)-linked $small{L}$-arabinofuranosyl residues of a branchless arabinan backbone to release arabinotriose mainly, although a small amount of arabino-oligosaccharide intermediates is also liberated. Our results indicated that BLABNase acts preferentially along with the oligosaccharides longer than arabinopentaose, thus enabling the enzymatic production of various arabino-oligosaccharides.