Nursing skills include many “Proficient skills” and “knacks”, it is said that the handing down them to new nurses is difficult because of their “tacit nature”. In this study, we devoted attention to biological data, such as the electroencephalographic (EEG) data, and their changes as a method for converting tacit knowledge into formal knowledge. We analyzed the characteristics, including the differences in the changing state of tension or concentration between nurses and beginners from the EEG data. In the experiment the participants were 2 nurses and 11 beginners who had no knowledge or experience of blood collecting skills. We divided the 11 beginners into two groups randomly to ascertain differences between Group 1 and Group 2. Group 1 comprised six beginners without a time limit for blood collection, whereas Group 2 comprised five beginners with a specific time limit (60 s). They performed blood collection skills 11 times each using an infusion and blood collection trainer (Adam, Rouilly Ltd.). We measured their EEG (in the prefrontal cortex area) at the time for comparison. For the analysis we used the β/α value as an indicator of tension and the θ/α value as an indicator of concentration of this time from the brain waves, and compared the β/α values with the θ/α values in each group (Group 1, Group 2, and nurses). Results revealed that nurses were in a state of concentration with calm during the performance with the predominant θ/α value. The β/α values were predominant with most beginners from Group 1. In contrast, θ/α values were predominant with most beginners from Group 2. Therefore, when beginners were given a time limit, they were able to concentrate on the sensitive task rather than become tense. Consequently, when beginners learn tense skills that demand physical aggression such as blood collection, some moderate limits are effective for beginners, especially in overly tense circumstances. We plan to analyze the differences between more nurses and more beginners and the processes by which beginners come to acquire proficiency, and to clarify characteristics of practical nursing knowledge.