The active transport, whether walking or cycling, contributes to increasing the level of physical activity of people. This habit could be favoured by acting on certain psychosocial factors, and by creating favourable environments. The purpose of the present study was to determine the perception of individual factors and of the nearby environment, related in a special way to each of the two modalities of active transport, in a population sample of the adults living in the metropolitan area of Pamplona. A cross-sectional study was conducted based on the methodology suggested by the International Physical Activity and the Environment Network Adult Group, which studies the relationship between environmental factors and physical activity practiced by adults. The results showed that the lack of time to practice physical activity was more likely to be associated with the group that walked less, OR 1.23 (1.08-1.40), and the lack of enjoyment of the physical activity with those who transport by bicycle less, OR 1.29 (1.04-1.61). Also, the existence of trees in the streets was associated with a greater probability of transport by walking, OR 1.23 (1.03-1.46), while the presence of signs or zebra crossings, which helped pedestrians to cross, was related to a wider use of the bycicle, OR 1.42 (1.08-1.87). In conclusion, certain characteristics of the individual and the environment are particularly associated with walking while others are with the use of the bicycle. Thus, people who spend less time walking to go from one place to another indicate lack of time as the reason that prevents them from carrying out some physical activity, while the group that uses the bicycle less to transport indicates lack of enjoyment. In addition, the presence of trees on the pavements favours and encourages people to travel by walking and the perception of intense traffic is associated with the group that dedicates less time to walking in order to go from one place to another. However, developing infrastructures that facilitate the mobility of pedestrians is associated with a greater use of the bicycle for active transport.