The cluster Zwicky 1615.8+3505 is considered to be a dynamically young poor cluster. To investigate the morphology and star-formation activity of galaxies under the environment of a dynamically young poor cluster, we have performed V , R, and I surface photometry, optical low-resolution spectroscopy, and 12 CO (J = 1 − 0) line observations for member galaxies. Our data show that more than 90% of the observed galaxies show regular morphologies and no star-1 formation activities, indicating that the environment does not affect these galaxy properties.Among sixteen galaxies observed, only NGC 6104 shows a significant star-formation activity, and shows a distorted morphology, indicating a tidal interaction. This galaxy contains double knots, and only one knot possesses Seyfert activity, though the sizes and luminosities are similar to each other; we also discuss this feature.Sports and Culture. † Research fellows of the Japan Society for the Promotion of Science. * The V -band magnitude and V − R and V − I colors within an isophotal ellipsoid of µ R = 23.5 mag arcsec −2 . The errors of measurements were estimated to be 0.02 mag for the magnitudes and colors, except for galaxies Nos. 12 and 14, the errors of which were estimated to be 0.1 mag. † The asymptotic total V -band magnitude and V − R and V − I colors. The errors of measurements were estimated to be 0.03 mag for the magnitudes and colors, except for galaxies Nos. 12 and 14, the errors of which were estimated to be 0.1 mag. ‡ The asymptotic total V -band magnitude and V − R and V − I colors correcting extinction and redshift effects. The errors of measurements were estimated to be 0.1 mag for the magnitudes and colors, except for galaxies Nos. 12 and 14, the errors of which were estimated to be 0.2 mag. 24