Ōka, Ohka, Ouka (おうか) or Ooka (おおか) may refer to:
- Ōka (桜花（おうか）), blossom of cherry tree
- Yokosuka MXY-7 Ohka (桜花（おうか）, Ōka), a Japanese kamikaze aircraft in World War II
- Ōka Station (相可（おうか）駅, Ōka-eki), a railway station
- Ōka (surname) (おうか or おおか), a Japanese surname