Collaborative learning has attracted attention as pedagogic mediation to assist learners' corpus consultation, but some studies have pointed to negative aspects of collaboration. Based on the two sides of collaboration in language learning, this study presents a qualitative investigation of different effects of collaboration depending on task types used in learners' corpus consultation. This study examined two types of tasks: a conceptual task, which tested students' competence to draw a generalizable conclusion through a meaning-making process of corpus consultation; and a procedural task, which asked students to complete problem-solving activities strategically through corpus analysis. Two groups of three students were given the same tasks of corpus consultation but asked to complete the tasks either collaboratively or individually. The students' verbal and nonverbal behaviors during the task completion, pre-and post-interviews, and the instructor's observation notes were the main sources of data for analysis. The results of this study showed that collaboration has significantly different effects depending on the task types of corpus consultation. The collaborative group (CG) outperformed the individual group (IG) in the conceptual corpus consultation task, but the procedural task was more efficiently completed by the IG than the CG. The underperformance of the CG in the procedural task seemed to be partly attributable to the role of established intersubjectivity and the power inequality in the CG. Despite some limitations, the findings of this study reveal task-dependent effects of collaboration in corpus consultation and suggest practical implications for more effective and pedagogically beneficial use of learners' corpus consultation in second language (L2) instruction.