This research aims to improve critical thinking skills and mathematics learning outcomes of grade IV students of SDN Tingkir Tengah 02. The subjects used in this study were 26 grade IV students consisting of 13 male students and 13 female students. The data collection technique carried out is using a test technique in the form of evaluation questions that have been tested for validity and reliability, then there is a non-test technique in the form of an observation sheet to assess learning activities using Problem Based Learning. The data obtained from the implementation of learning were analyzed descriptively. The results of the research conducted showed that there was an increase in students' critical thinking skills, where in cycle 1 there were 20 students (77%) who had a high category of critical thinking skills and in cycle 2 there were 23 students (88.5%). In addition, student learning outcomes have also improved, where in cycle 1 there are 18 students (69%) who complete and in cycle 2 there are 23 students (88.5%). So based on the results of the above data analysis, it can be concluded that the application of the Problem Based Learning model is able to improve the critical thinking skills and mathematics learning outcomes of grade IV students of SDN Tingkir Tengah 02. ABSTRAKPenelitian ini bertujuan untuk meningkatkan keterampilan berpikir kritis dan hasil belajar matematika siswa kelas IV SDN Tingkir Tengah 02. Subjek yang digunakan dalam penelitian ini adalah 26 siswa kelas IV yang terdiri dari 13 siswa laki-laki dan 13 siswa perempuan. Teknik pengumpulan data yang dilakukan yaitu menggunakan teknik tes berupa soal evaluasi yang telah diuji validitas dan reliabilitas, kemudian terdapat teknik non tes berupa lembar observasi untuk menilai aktivitas pembelajaran menggunakan Problem Based Learning. Data yang diperoleh dari implementasi pembelajaran, dilakukan analisis statistik deskriptif. Hasil penelitian yang dilakukan menunjukkan bahwa terjadi kenaikan pada keterampilan berpikir kritis siswa, di mana pada siklus 1 terdapat 20 siswa (77%) yang memiliki kategori keterampilan berpikir kritis tinggi dan pada siklus 2 terdapat 23 siswa (88,5 %). Selain itu hasil belajar siswa juga mengalami peningkatan, di mana pada siklus 1 terdapat 18 siswa (69%) yang tuntas dan siklus 2 terdapat 23 siswa (88,5%). Sehingga berdasarkan hasil analisis data di atas dapat disimpulkan bahwa penerapan model Problem Based Learning mampu meningkatkan keterampilan berpikir kritis dan hasil belajar matematika siswa kelas IV SDN Tingkir Tengah 02.