  A direction-sensitive dark matter search experiment at Kamioka underground
laboratory with the NEWAGE-0.3a detector was performed. The NEWAGE- 0.3a
detector is a gaseous micro-time-projection chamber filled with CF4 gas at 152
Torr. The fiducial volume and target mass are 20*25*31 cm3 and 0.0115 kg,
respectively. With an exposure of 0.524 kgdays, improved spin-dependent weakly
interacting massive particle (WIMP)-proton cross section limits by a
direction-sensitive method were achieved including a new record of 5400 pb for
150 GeV/c2 WIMPs. We studied the remaining background and found that ambient
gamma-rays contributed about one-fifth of the remaining background and
radioactive contaminants inside the gas chamber contributed the rest.
