Women in Indonesia are now increasingly showing their existence in the world of work. The need for working mothers to be able to balance work and household responsibilities as well as the dynamics that occur in children in the age range of elementary school children (middle childhood) can be a source of stress that triggers parenting stress. Previous research has proven that hardiness has a negative correlation with parenting stress, but has not explained further about the effect of hardiness on parenting stress, specifically for working mothers who care for elementary school-aged children with normal development. Therefore, this study aims to further examine the effect of hardiness as an individual internal factor on parenting stress in working mothers who care for middle childhood children. The research design used was cross-sectional with the Multidimensional Hardiness Inventory for Young Adults (MHIYA-18) and the Parental Stress Scale (PSS) measuring instruments. A total of 256 working mothers in DKI Jakarta participated in this study, which were obtained through purposive sampling and snowball sampling methods. The results of the study show that hardiness does not significantly influence parenting stress, this is due to the uneven distribution of data. This study reconfirms that there is a negative correlation between hardiness and parenting stress (r=-0.438, p<.001) through 256 participants. / Wanita di Indonesia kini semakin menunjukkan eksistensi mereka dalam dunia kerja. Kebutuhan ibu bekerja untuk dapat menyeimbangkan tanggung jawab pekerjaan dan rumah tangga serta dinamika yang terjadi pada anak dalam rentang usia anak sekolah dasar (middle childhood) dapat menjadi sumber stres yang memicu parenting stress. Penelitian terdahulu telah membuktikan jika hardiness memiliki korelasi negatif dengan parenting stress, namun belum menjelaskan lebih lanjut terkait dengan pengaruh hardiness terhadap parenting stress secara khusus pada ibu bekerja yang mengasuh anak usia sekolah dasar dengan perkembangan normal. Oleh karena itu, studi ini bertujuan untuk meneliti lebih lanjut pengaruh hardiness sebagai faktor internal individu terhadap parenting stress pada ibu bekerja yang mengasuh anak usia sekolah dasar (middle childhood). Desain penelitian yang digunakkan adalah cross-sectional dengan alat ukur Multidimensional Hardiness Inventory for Young Adults (MHIYA-18) dan Parental Stress Scale (PSS). Sebanyak 256 ibu bekerja di DKI Jakarta berpartisipasi dalam penelitian ini, yang didapat melalui metode purposive sampling dan snowball sampling. Hasil penelitian menunjukan hardiness tidak berpengaruh secara signifikan terhadap parenting stress, hal ini dikarenakan penyebaran data kurang merata. Penelitian ini mengkonfirmasi kembali bahwa terdapat korelasi negatif antara hardiness dengan parenting stress (r=-0.438, p<.001) melalui 256 partisipan.