The objective of this study is to examine the effect of the determinization level of the design task on the dynamics of design activity as well as on design problems, process, and solutions. With design tasks at two different determinization levels, we conducted protocol analysis based on the Triad categories and Determinization categories, and administered comparative questionnaires about design problems, process, and solutions. In regards to the Triad categories, designers identified the problems of the existing solutions and created solutions in the earlier stage of the design process when solving the low determinization level design task. About the Determinization categories, designers increased the determinization level more when solving the high determinization level design task. In the case of the low determinization level design task, the problem was easier and more interesting, and the solution was more appropriate, beautiful, creative, useful, and better. In addition, the process of the low determinization level task was easier, more interesting and creative. Designers were better at concept generation and redefining the design problem when solving the low determinization level task. On the other hand, in the case of the high determinization level design task, the process was more concrete and planned, and the solution displayed higher usability.