A gear fluid device comprising: a drive gear and a driven gear to be engaged with each other; sliding contact members (5, 6, 220, 220, 320, 330) having sliding contact surfaces to be brought into sliding contact with a side face of the drive gear and a side face of the driven gear, rotary shaft holes (5a, 5b) into which rotary shafts (11, 12) of the drive gear and the driven gear are inserted respectively, and clearance grooves (51, 52) which allow confinement regions formed at engagement portions of the drive gear and the driven gear to be communicated with a low pressure side and a high pressure side, respectively; and groove portions (53, 54, 55, 56) which are provided in the sliding contact surfaces of the sliding contact members (5, 6, 220, 220, 320, 330), the groove portions having one end portion opening to the rotary shaft holes (5a, 5b) or the clearance grooves (51, 52), and another end portion opposite to the one end portion that is positioned radially inside root diameters of the drive gear and the driven gear and moreover radially outside the rotary shaft holes (5a, 5b), wherein there are no groove portions, in the sliding contact surfaces of the sliding contact members (5, 6, 220, 220, 320, 330), which extend from radially outside root diameters of the drive gear and the driven gear to the rotary shaft holes (5a, 5b), and which open to the rotary shaft holes (5a, 5b), characterized in that at least one of the groove portions (53, 54) of the sliding contact members (5, 6) is provided so as to connecting to the clearance groove, and another at least one of the groove portions (55, 56) of the sliding contact members (5, 6) is provided so as to connecting to the rotary shaft hole (5a, 5b) and a radially-inner end portion of at least one of the groove portions (53, 54) connecting to the clearance groove of the sliding contact members (5, 6) is positioned radially inside a radially-outer end portion of the at least one of the groove portions (55, 56) connecting to the rotary shaft hole (5a, 5b) of the sliding contact members (5, 6). a drive gear and a driven gear to be engaged with each other; sliding contact members (5, 6, 220, 220, 320, 330) having sliding contact surfaces to be brought into sliding contact with a side face of the drive gear and a side face of the driven gear, rotary shaft holes (5a, 5b) into which rotary shafts (11, 12) of the drive gear and the driven gear are inserted respectively, and clearance grooves (51, 52) which allow confinement regions formed at engagement portions of the drive gear and the driven gear to be communicated with a low pressure side and a high pressure side, respectively; and groove portions (53, 54, 55, 56) which are provided in the sliding contact surfaces of the sliding contact members (5, 6, 220, 220, 320, 330), the groove portions having one end portion opening to the rotary shaft holes (5a, 5b) or the clearance grooves (51, 52), and another end portion opposite to the one end portion that is positioned radially inside root diameters of the drive gear and the driven gear and moreover radially outside the rotary shaft holes (5a, 5b), wherein there are no groove portions, in the sliding contact surfaces of the sliding contact members (5, 6, 220, 220, 320, 330), which extend from radially outside root diameters of the drive gear and the driven gear to the rotary shaft holes (5a, 5b), and which open to the rotary shaft holes (5a, 5b), at least one of the groove portions (53, 54) of the sliding contact members (5, 6) is provided so as to connecting to the clearance groove, and another at least one of the groove portions (55, 56) of the sliding contact members (5, 6) is provided so as to connecting to the rotary shaft hole (5a, 5b) and a radially-inner end portion of at least one of the groove portions (53, 54) connecting to the clearance groove of the sliding contact members (5, 6) is positioned radially inside a radially-outer end portion of the at least one of the groove portions (55, 56) connecting to the rotary shaft hole (5a, 5b) of the sliding contact members (5, 6).