We present the results 12CO J = 1–0 line observations of eleven Galactic supernova remnants (SNRs) between l = 70° and 190° obtained using the Seoul Radio Astronomy Observatory (SRAO) 6-m radio telescope. We detected CO emission towards most of the remnants. In seven SNRs, molecular clouds show a good spatial relation with their radio morphology: G73.9+0.9, G84.2−0.8, G85.4+0.7, G85.9−0.6, G93.3+6.9 (DA530), 94.0+1.0 (3C 434.1), and G182.4+4.3. Two SNRs are particularly interesting. In G85.4+0.7, there is a filamentary molecular cloud aligned along the south-east boundary of the remnant. This cloud extends to the nearby Hii region G84.9+0.5. If the molecular cloud is associated with both the Hii region and the SNR, the distance to the SNR would be 5–7 kpc. In 3C 434.1, there is a large molecular cloud blocking the western half of the remnant where the radio continuum emission is faint. The cloud shows a very good spatial correlation with radio continuum features, which strongly suggests the physical association of the cloud with the SNR. This gives a distance of 3 kpc to the SNR. We performed 12CO J = 2–1 line observations of this cloud using Kölner Observatorium für Sub-Millimeter Astronomie (KOSMA) 3-m telescope and found a region where the 12CO J = 2–1/1–0 line ratio is high. We present a hydrodynamic model showing that 3C434.1 could have resulted from a SN explosion occurred just outside the boundary of a thin, molecular cloud.