The paper considers the feeling of security among inmates in Polish prisons and detention facilities. The adopted methods include the diagnostic survey method, and statistical and comparative analysis method, including factor analysis. The research conducted in five randomly selected Polish prisons and detention facilities included a sample of 392 inmates. Factors significant for the physical and social prison space were analysed. No correlation was found between the sense of security of persons deprived of their liberty and the time spent in a residential cell and the duration of stay and number of transfers in the prison/detention facility. However, it was noted that with the age increase, the “anxiety” of first-time inmates who did not participate in the subculture of prison cryptolect decreased (N=72, Spearman’s rho correlation = -0.247, p < 0.05) and the “fear of inmates’ threatening behaviour” among the prisoners who served a prison sentence again, and who did not participate in the subculture of prison cryptolect, was reduced (N=262, Spearman’s rho correlation = -0.221, p < 0.01). It was also found that the greater the number of inmates in a residential cell, the lower the “fear of inmates’ threatening behaviour” (N=48, Kendall’s tau-b correlation =-0.293, p < 0.01) among the participants in the subculture of prison cryptolect who serve a prison sentence again.