Ice floe distribution in the Sea of Okhotsk during a cold‐air outbreak was investigated by analyzing several thousand of sea‐ice images obtained by the aircraft observation on 18 February in 2000. The effective floe size became small (from 10 m to 2 m) within the marginal ice zone (MIZ). The scaling properties of floe distribution are demonstrated by a cumulative number frequency which follows a power law scaling with an exponent α. The value of α increased from 1.5 within the internal ice zone to 2.1 within the MIZ, which means that relatively small ice floes dominate in the MIZ. The effective width of the MIZ estimated by a wave attenuation theory agreed with the observed width, suggesting that the flexural stress of waves penetrating into the ice is one of the possible mechanisms which cause the difference in the scaling property.