Purpose : The purpose is to analyze the relationship between bone bruise in MRI and associated injuries after the knee joint trauma. Materials and Methods : Total 50 cases were reviewed, divided into two groups according to initial trauma energy. High-energy group (group I), such as traffic accident was 13 cases, low-energy group (group II), such as sports trauma was 37 cases. The type of the lesion was used the classification by Costa-Paz. The site of lesion was analyzed according to femoral/tibial, medial/lateral and anterior/middle/posterior site respectively. Associated injuries were confirmed by physical examination, radiograph, MRI and arthroscopy. Results : In group I there was a various distribution of the bone bruise in the knee joint according to mechanism of injury. The bone bruise with ACL injury was 38$\%$ only and the most frequent type was Costa-Paz type I (52.6 $\%$). In group II more frequent locations were the middle portion of the lateral femoral condyle and the posterior portion of the lateral tibial condyle. Bone bruise associated with ACL injury, was upto 56.8 $\%$ and the frequent type were Costa-Paz type II (48 $\%$), in order type I (42 $\%$). As a result, in the high-energy injury the bone bruise had a various location in both condyle and less frequently associated injury, but in the low-energy injury there was particularly frequent location of bone bruise, associated injury and type. Conclusions : We could assess the associated injury by analysis of the location and type of bone bruise, especially in the low-energy injury, e.g. sports injury. But further study will be necessary with more case analysis.