Real sea waves are well known to have a property of directional randomness. Reproduction of waves with such property in laboratories is much desired for the studies of wave transformations, wave and structure interactions, and others.
　The present paper investigates the properties of the oblique waves theoretically. First, the formula of waves generated by a single wave paddle is obtained theoretically, and the properties of the wave height and propagating angle are investigated by the computation of the formula. The validity of the formulation is confirmed by the comparison of the computed wave heights to the experimental ones.
　Second, the formula of the oblique waves is obtained as the linear superposition of the above formula by controlling the phase difference between the motions of adjacent wavemakers. The formula predicts that the oblique waves generated by serpent-type wavemakers vary in their heights and propagating angles. The variation consists of ripple and undulation pattern, and cannot be made to disappear, even if the width of each paddle is reduced to infinitesimal value.
　Finally, the effect of wave reflection from the side walls is analysed by applying the mirror image method, and some numerical results are presented.